Donghui Lu

All Publications

• One-Dimensional Electron Gas Confined along Nanowrinkles in a Unidirectional Charge Density Wave Material. ACS nano Kim, E., Lee, S., Yang, H., Hashimoto, M., Lu, D., Park, J., Kim, C., Wulferding, D., Kim, S., Cho, D. 2025

  Abstract

  Two-dimensional (2D) materials inherently exhibit instabilities. Structurally, this may lead to modulations along the third dimension, e.g., wrinkles. Electronically, 2D instabilities can manifest themselves as charge density waves (CDWs). Although wrinkles can alter anisotropic electronic structures susceptible to forming CDWs, less is known about their impact on broken-symmetry ground states. Here, using scanning tunneling microscopy and spectroscopy, we investigate the CDW states on the wrinkled surface of DyTe3. We identify elongated, parallel nanoscale wrinkles stabilized by ribbon-shaped defects. Interestingly, the CDW order persists across the nanowrinkles with a gradual phase shift but is locally suppressed near the defects, where phase windings occur. In addition, these defects induce quantum confinement effects along the nanowrinkles, indicating the presence of one-dimensional metallic states with hole-like dispersion, while angle-resolved photoemission spectroscopy identifies a gap along the wrinkle direction. We ascribe this discrepancy to strain-induced changes in the Fermi surface, which lead to the closure of the gap at the sites of the nanowrinkles. Taken together, our results underscore the complex interplay between structural features and Fermi surface topology, allowing for the deliberate manipulation of quantum states in strongly correlated systems via local crystal deformations.

  View details for DOI 10.1021/acsnano.4c18943

  View details for PubMedID 40252038

• Electron correlation and incipient flat bands in the Kagome superconductor CsCr3Sb5. Nature communications Li, Y., Liu, Y., Du, X., Wu, S., Zhao, W., Zhai, K., Hu, Y., Zhang, S., Chen, H., Liu, J., Yang, Y., Peng, C., Hashimoto, M., Lu, D., Liu, Z., Wang, Y., Chen, Y., Cao, G., Yang, L. 2025; 16 (1): 3229

  Abstract

  Correlated kagome materials exhibit a compelling interplay between lattice geometry, electron correlation, and topology. In particular, the flat bands near the Fermi level provide a fertile playground for novel many-body states. Here we investigate the electronic structure of CsCr3Sb5 using high-resolution angle-resolved photoemission spectroscopy and ab-initio calculations. Our results suggest that Cr 3d electrons are intrinsically incoherent, showing strong electron correlation amplified by Hund's coupling. Notably, we identify incipient flat bands close to the Fermi level, which are expected to significantly influence the electronic properties of the system. Across the density-wave-like transition at 55K, we observe a drastic enhancement of the electron scattering rate, which aligns with the semiconducting-like property at high temperatures. These findings establish CsCr3Sb5 as a strongly correlated Hund's metal with incipient flat bands near the Fermi level, which provides an electronic basis for understanding its novel properties compared to the weakly correlated AV3Sb5.

  View details for DOI 10.1038/s41467-025-58487-x

  View details for PubMedID 40185734

• Near-half-metallic state in the half-Heusler PtMnSb film on a III-V substrate PHYSICAL REVIEW MATERIALS Nishihaya, S., Jardine, M. A., Inbar, H. S., Goswami, A., Dong, J. T., Engel, A. N., Chang, Y., Dempsey, C. P., Hashimoto, M., Lu, D., Marom, N., Palmstrom, C. J. 2025; 9 (4)

  View details for DOI 10.1103/PhysRevMaterials.9.044403

  View details for Web of Science ID 001465116700003

• Electronic Structure of the Alternating Monolayer-Trilayer Phase of La_{3}Ni_{2}O_{7}. Physical review letters Abadi, S., Xu, K. J., Lomeli, E. G., Puphal, P., Isobe, M., Zhong, Y., Fedorov, A. V., Mo, S. K., Hashimoto, M., Lu, D. H., Moritz, B., Keimer, B., Devereaux, T. P., Hepting, M., Shen, Z. X. 2025; 134 (12): 126001

  Abstract

  Recent studies of La_{3}Ni_{2}O_{7} have identified a bilayer (2222) structure and an unexpected alternating monolayer-trilayer (1313) structure, both of which feature signatures of superconductivity near 80 K under high pressures. Using angle-resolved photoemission spectroscopy, we measure the electronic structure of 1313 samples. In contrast to the previously studied 2222 structure, we find that the 1313 structure hosts a flat band with a markedly different binding energy, as well as an additional electron pocket and band splittings. By comparison to local-density approximation calculations, we find renormalizations of the Ni-d_{z^{2}} and Ni-d_{x^{2}-y^{2}} derived bands to be about 5 to 7 and about 4, respectively, suggesting strong correlation effects. These results reveal important differences in the electronic structure brought about by the distinct structural motifs with the same stoichiometry. Such differences may be relevant to the putative high temperature superconductivity.

  View details for DOI 10.1103/PhysRevLett.134.126001

  View details for PubMedID 40215506

• Floquet-Bloch manipulation of the Dirac gap in a topological antiferromagnet NATURE PHYSICS Bielinski, N., Chari, R., May-Mann, J., Kim, S., Zwettler, J., Deng, Y., Aishwarya, A., Roychowdhury, S., Shekhar, C., Hashimoto, M., Lu, D., Yan, J., Felser, C., Madhavan, V., Shen, Z., Hughes, T. L., Mahmood, F. 2025

  View details for DOI 10.1038/s41567-024-02769-6

  View details for Web of Science ID 001401138700001

• Pseudogap in electron-doped cuprates: Strong correlation leading to band splitting. Proceedings of the National Academy of Sciences of the United States of America Horio, M., Sakai, S., Suzuki, H., Nonaka, Y., Hashimoto, M., Lu, D., Shen, Z., Ohgi, T., Konno, T., Adachi, T., Koike, Y., Imada, M., Fujimori, A. 2025; 122 (1): e2406624122

  Abstract

  The pseudogap phenomena have been a long-standing mystery of the cuprate high-temperature superconductors. The pseudogap in the electron-doped cuprates has been attributed to band folding due to antiferromagnetic (AFM) long-range order or short-range correlation. We performed an angle-resolved photoemission spectroscopy study of the electron-doped cuprates Pr1.3-xLa0.7CexCuO4 showing spin-glass, disordered AFM behaviors, and superconductivity at low temperatures and, by measurements with fine momentum cuts, found that the gap opens on the unfolded Fermi surface rather than the AFM Brillouin zone boundary. The gap did not show a node, following the full symmetry of the Brillouin zone, and its magnitude decreased from the zone-diagonal to (pi,0) directions, opposite to the hole-doped case. These observations were reproduced by cluster dynamical-mean-field-theory calculation, which took into account electron correlation precisely within a (CuO2)4 cluster. The present experimental and theoretical results are consistent with the mechanism that electron or hole doping into a Mott insulator creates an in-gap band that is separated from the upper or lower Hubbard band by the pseudogap.

  View details for DOI 10.1073/pnas.2406624122

  View details for PubMedID 39793056

• Colossal magnetoresistance from spin-polarized polarons in an Ising system. Proceedings of the National Academy of Sciences of the United States of America Li, Y. F., Been, E. M., Balguri, S., Jia, C. J., Mahendru, M. B., Wang, Z. C., Cui, Y., Chen, S. D., Hashimoto, M., Lu, D. H., Moritz, B., Zaanen, J., Tafti, F., Devereaux, T. P., Shen, Z. X. 2024; 121 (50): e2409846121

  Abstract

  Recent experiments suggest a new paradigm toward novel colossal magnetoresistance (CMR) in a family of materials EuM[Formula: see text]X[Formula: see text] (M [Formula: see text] Cd, In, Zn; X [Formula: see text] P, As), distinct from the traditional avenues involving Kondo-Ruderman-Kittel-Kasuya-Yosida crossovers, magnetic phase transitions with structural distortions, or topological phase transitions. Here, we use angle-resolved photoemission spectroscopy and density functional theory calculations to explore their origin, particularly focusing on EuCd[Formula: see text]P[Formula: see text]. While the low-energy spectral weight royally tracks that of the resistivity anomaly near the temperature with maximum magnetoresistance ([Formula: see text]) as expected from transport-spectroscopy correspondence, the spectra are completely incoherent and strongly suppressed with no hint of a Landau quasiparticle. Using systematic material and temperature dependence investigation complemented by theory, we attribute this nonquasiparticle caricature to the strong presence of entangled magnetic and lattice interactions, a characteristic enabled by the [Formula: see text]-[Formula: see text] mixing. Given the known presence of ferromagnetic clusters, this naturally points to the origin of CMR being the scattering of spin-polarized polarons at the boundaries of ferromagnetic clusters. These results are not only illuminating to investigate the strong correlations and topology in EuCd[Formula: see text]X[Formula: see text] family, but, in a broader view, exemplify how multiple cooperative interactions can give rise to extraordinary behaviors in condensed matter systems.

  View details for DOI 10.1073/pnas.2409846121

  View details for PubMedID 39621914

• Dispersion kinks from electronic correlations in an unconventional iron-based superconductor NATURE COMMUNICATIONS Chang, M., Backes, S., Lu, D., Gauthier, N., Hashimoto, M., Chen, G., Wen, H., Mo, S., Valenti, R., Pfau, H. 2024; 15 (1): 9958

  Abstract

  The attractive interaction in conventional BCS superconductors is provided by a bosonic mode. However, the pairing glue of most unconventional superconductors is unknown. The effect of electron-boson coupling is therefore extensively studied in these materials. A key signature is dispersion kinks that can be observed in the spectral function as abrupt changes in velocity and lifetime of quasiparticles. Here, we show the existence of two kinks in the unconventional iron-based superconductor RbFe2As2 using angle-resolved photoemission spectroscopy (ARPES) and dynamical mean field theory (DMFT). In addition, we observe the formation of a Hubbard band multiplet due to the combination of Coulomb interaction and Hund's rule coupling in this multiorbital system. We demonstrate that the two dispersion kinks are a consequence of these strong many-body interactions. This interpretation is in line with a growing number of theoretical predictions for kinks in various general models of correlated materials. Our results provide a unifying link between iron-based superconductors and different classes of correlated, unconventional superconductors such as cuprates and heavy-fermion materials.

  View details for DOI 10.1038/s41467-024-54330-x

  View details for Web of Science ID 001356474000010

  View details for PubMedID 39551803

  View details for PubMedCentralID PMC11570641

• Observation of flat bands and Dirac cones in a pyrochlore lattice superconductor NPJ QUANTUM MATERIALS Huang, J., Setty, C., Deng, L., You, J., Liu, H., Shao, S., Oh, J., Guo, Y., Zhang, Y., Yue, Z., Yin, J., Hashimoto, M., Lu, D., Gorovikov, S., Dai, P., Denlinger, J. D., Allen, J. W., Hasan, M., Feng, Y., Birgeneau, R. J., Shi, Y., Chu, C., Chang, G., Si, Q., Yi, M. 2024; 9 (1)

  View details for DOI 10.1038/s41535-024-00683-x

  View details for Web of Science ID 001316044100001

• Coupling Between Electrons and Charge Density Wave Fluctuation and its Possible Role in Superconductivity. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Lee, Y., Sur, Y., Kim, S., Cha, J., Hyun, J., Lim, C., Hashimoto, M., Lu, D., Kim, Y., Huh, S., Kim, C., Ideta, S., Tanaka, K., Kim, K. H., Kim, Y. 2024: e2406043

  Abstract

  In most charge density wave (CDW) systems of different material classes, ranging from traditional correlated systems in low-dimension to recent topological systems with Kagome lattice, superconductivity emerges when the system is driven toward the quantum critical point (QCP) of CDW via external parameters of doping and pressure. Despite this rather universal trend, the essential hinge between CDW and superconductivity has not been established yet. Here, the evidence of coupling between electron and CDW fluctuation is reported, based on a temperature- and intercalation-dependent kink in the angle-resolved photoemission spectra of 2H-PdxTaSe2. Kinks are observed only when the system is in the CDW phase, regardless of whether a long- or short-range order is established. Notably, the coupling strength is enhanced upon long-range CDW suppression, albeit the coupling energy scale is reduced. Interestingly, the estimation of the superconducting critical temperature by incorporating the observed coupling characteristics into McMillan's equation yields results closely resembling the known values of the superconducting dome. The results thus highlight a compelling possibility that this new coupling mediates Cooper pairs, which provides new insights into the competing relationship not only for CDW but also for other competing orders.

  View details for DOI 10.1002/advs.202406043

  View details for PubMedID 39234922

• Robust Weak Topological Insulator in the Bismuth Halide Bi_{4}Br_{2}I_{2}. Physical review letters Noguchi, R., Kobayashi, M., Kawaguchi, K., Yamamori, W., Aido, K., Lin, C., Tanaka, H., Kuroda, K., Harasawa, A., Kandyba, V., Cattelan, M., Barinov, A., Hashimoto, M., Lu, D., Ochi, M., Sasagawa, T., Kondo, T. 2024; 133 (8): 086602

  Abstract

  We apply a topological material design concept for selecting a bulk topology of 3D crystals by different van der Waals stackings of 2D topological insulator layers, and find a bismuth halide Bi_{4}Br_{2}I_{2} to be an ideal weak topological insulator (WTI) with the largest band gap (300meV) among all the WTI candidates, by means of angle-resolved photoemission spectroscopy (ARPES), density functional theory (DFT) calculations, and resistivity measurements. Furthermore, we reveal that the topological surface state of a WTI is not "weak" but rather robust against external perturbations against the initial theoretical prediction by performing potassium deposition experiments. Our results vastly expand future opportunities for fundamental research and device applications with a robust WTI.

  View details for DOI 10.1103/PhysRevLett.133.086602

  View details for PubMedID 39241706

• Anomalous normal-state gap in an electron-doped cuprate. Science (New York, N.Y.) Xu, K. J., He, J., Chen, S. D., He, Y., Abadi, S. N., Rotundu, C. R., Lee, Y. S., Lu, D. H., Guo, Q., Tjernberg, O., Devereaux, T. P., Lee, D. H., Hashimoto, M., Shen, Z. X. 2024; 385 (6710): 796-800

  Abstract

  In the underdoped n-type cuprate Nd2-xCexCuO4, long-range antiferromagnetic order reconstructs the Fermi surface, resulting in a putative antiferromagnetic metal with small Fermi pockets. Using angle-resolved photoemission spectroscopy, we observe an anomalous energy gap, an order of magnitude smaller than the antiferromagnetic gap, in a wide portion of the underdoped regime and smoothly connecting to the superconducting gap at optimal doping. After considering all the known ordering tendencies in tandem with the phase diagram, we hypothesize that the normal-state gap in the underdoped n-type cuprates originates from Cooper pairing. The high temperature scale of the normal-state gap raises the prospect of engineering higher transition temperatures in the n-type cuprates comparable to those of the p-type cuprates.

  View details for DOI 10.1126/science.adk4792

  View details for PubMedID 39146411

• Fermi Surface Nesting Driving the RKKY Interaction in the Centrosymmetric Skyrmion Magnet Gd 2 PdSi 3 PHYSICAL REVIEW LETTERS Dong, Y., Arai, Y., Kuroda, K., Ochi, M., Tanaka, N., Wan, Y., Watson, M. D., Kim, T. K., Cacho, C., Hashimoto, M., Lu, D., Aoki, Y., Matsuda, T. D., Kondo, T. 2024; 133 (1)

  View details for DOI 10.1103/PhysRevLett.133.016401

  View details for Web of Science ID 001262611100004

• Electronic structure and effective mass of pristine and Cl-doped CsPbBr₃ CHINESE PHYSICS B Wei, Z., Wei, Y., Xu, S., Peng, S., Hashimoto, M., Lu, D., Pan, X., Kuang, M., Xiao, Z., He, J. 2024; 33 (5)

  View details for DOI 10.1088/1674-1056/ad3c31

  View details for Web of Science ID 001223231000001

• Growth and characterization of α-Sn thin films on In- and Sb-rich reconstructions of InSb(001) PHYSICAL REVIEW MATERIALS Engel, A. N., Dempsey, C. P., Inbar, H. S., Dong, J. T., Nishihaya, S., Chang, Y., V. Fedorov, A., Hashimoto, M., Lu, D., Palmstrom, C. J. 2024; 8 (4)

  View details for DOI 10.1103/PhysRevMaterials.8.044202

  View details for Web of Science ID 001221969500001

• Beyond Conventional Charge Density Wave for Strongly Enhanced Two-dimensional Superconductivity in 1H-TaS2Superlattices. Advanced materials (Deerfield Beach, Fla.) Li, Z., Lyu, P., Chen, Z., Guan, D., Yu, S., Zhao, J., Huang, P., Zhou, X., Qiu, Z., Fang, H., Hashimoto, M., Lu, D., Song, F., Loh, K. P., Zheng, Y., Shen, Z., Novoselov, K. S., Lu, J. 2024: e2312341

  Abstract

  Noncentrosymmetric transition metal dichalcogenide (TMD) monolayers offer a fertile platform for exploring unconventional Ising superconductivity (SC) and charge density waves (CDWs). However, the vulnerability of isolated monolayers to structural disorder and environmental oxidation often degrade their electronic coherence. Herein, we report an alternative approach for fabricating stable and intrinsic monolayers of 1H-TaS2 sandwiched between SnS blocks in a (SnS)1.15TaS2 van der Waals (vdW) superlattice. The SnS block layers not only decouple individual 1H-TaS2 sublayers to endow them with monolayer-like electronic characteristics, but also protect the 1H-TaS2 layers from electronic degradation. The results reveal the characteristic 3 * 3 CDW order in 1H-TaS2 sublayers associated with electronic rearrangement in the low-lying S p band, which uncovers a previously undiscovered CDW mechanism rather than the conventional Fermi surface-related framework. Additionally, the (SnS)1.15TaS2 superlattice exhibits a strongly enhanced Ising-like SC with a layer-independent Tc of approximately 3.0 K, comparable to that of the isolated monolayer 1H-TaS2 sample, presumably attributed to their monolayer-like characteristics and retained Fermi states. Our results provide new insights into the long-debated CDW order and enhanced SC of monolayer 1H-TaS2, establishing bulk vdW superlattices as promising platforms for investigating exotic collective quantum phases in the two-dimensional limit. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/adma.202312341

  View details for PubMedID 38567889

• Reversible non-volatile electronic switching in a near-room-temperature van der Waals ferromagnet. Nature communications Wu, H., Chen, L., Malinowski, P., Jang, B. G., Deng, Q., Scott, K., Huang, J., Ruff, J. P., He, Y., Chen, X., Hu, C., Yue, Z., Oh, J. S., Teng, X., Guo, Y., Klemm, M., Shi, C., Shi, Y., Setty, C., Werner, T., Hashimoto, M., Lu, D., Yilmaz, T., Vescovo, E., Mo, S., Fedorov, A., Denlinger, J. D., Xie, Y., Gao, B., Kono, J., Dai, P., Han, Y., Xu, X., Birgeneau, R. J., Zhu, J., da Silva Neto, E. H., Wu, L., Chu, J., Si, Q., Yi, M. 2024; 15 (1): 2739

  Abstract

  Non-volatile phase-change memory devices utilize local heating to toggle between crystalline and amorphous states with distinct electrical properties. Expanding on this kind of switching to two topologically distinct phases requires controlled non-volatile switching between two crystalline phases with distinct symmetries. Here, we report the observation of reversible and non-volatile switching between two stable and closely related crystal structures, with remarkably distinct electronic structures, in the near-room-temperature van der Waals ferromagnet Fe5-deltaGeTe2. We show that the switching is enabled by the ordering and disordering of Fe site vacancies that results in distinct crystalline symmetries of the two phases, which can be controlled by a thermal annealing and quenching method. The two phases are distinguished by the presence of topological nodal lines due to the preserved global inversion symmetry in the site-disordered phase, flat bands resulting from quantum destructive interference on a bipartite lattice, and broken inversion symmetry in the site-ordered phase.

  View details for DOI 10.1038/s41467-024-46862-z

  View details for PubMedID 38548765

• Author Correction: Kondo interaction in FeTe and its potential role in the magnetic order. Nature communications Kim, Y., Kim, M., Kim, D., Kim, M., Kim, M., Cheng, C., Choi, J., Jung, S., Lu, D., Kim, J. H., Cho, S., Song, D., Oh, D., Yu, L., Choi, Y. J., Kim, H., Han, J. H., Jo, Y., Shim, J. H., Seo, J., Huh, S., Kim, C. 2024; 15 (1): 2427

  View details for DOI 10.1038/s41467-024-46779-7

  View details for PubMedID 38499568

• Spontaneous Gap Opening and Potential Excitonic States in an Ideal Dirac Semimetal Ta₂Pd₃Te₅ PHYSICAL REVIEW X Zhang, P., Dong, Y., Yan, D., Jiang, B., Yang, T., Li, J., Guo, Z., Huang, Y., Haobo, Li, Q., Li, Y., Kurokawa, K., Wang, R., Nie, Y., Hashimoto, M., Lu, D., Jiao, W., Shen, J., Qian, T., Wang, Z., Shi, Y., Kondo, T. 2024; 14 (1)

  View details for DOI 10.1103/PhysRevX.14.011047

  View details for Web of Science ID 001325397000001

• Spectral evidence for local-moment ferromagnetism in the van der Waals metals Fe₃GaTe₂ and Fe₃GeTe₂ PHYSICAL REVIEW B Wu, H., Hu, C., Xie, Y., Jang, B., Huang, J., Guo, Y., Wu, S., Hu, C., Yue, Z., Shi, Y., Basak, R., Ren, Z., Yilmaz, T., Vescovo, E., Jozwiak, C., Bostwick, A., Rotenberg, E., Fedorov, A., Denlinger, J. D., Klewe, C., Shafer, P., Lu, D., Hashimoto, M., Kono, J., Frano, A., Birgeneau, R. J., Xu, X., Zhu, J., Dai, P., Chu, J., Yi, M. 2024; 109 (10)

  View details for DOI 10.1103/PhysRevB.109.104410

  View details for Web of Science ID 001249295000001

• Nanoscale visualization and spectral fingerprints of the charge order in ScV₆Sn₆ distinct from other kagome metals NPJ QUANTUM MATERIALS Cheng, S., Ren, Z., Li, H., Oh, J., Tan, H., Pokharel, G., DeStefano, J. M., Rosenberg, E., Guo, Y., Zhang, Y., Yue, Z., Lee, Y., Gorovikov, S., Zonno, M., Hashimoto, M., Lu, D., Ke, L., Mazzola, F., Kono, J., Birgeneau, R. J., Chu, J., Wilson, S. D., Wang, Z., Yan, B., Yi, M., Zeljkovic, I. 2024; 9 (1)

  View details for DOI 10.1038/s41535-024-00623-9

  View details for Web of Science ID 001152410800001

• Non-Fermi liquid behaviour in a correlated flat-band pyrochlore lattice NATURE PHYSICS Huang, J., Chen, L., Huang, Y., Setty, C., Gao, B., Shi, Y., Liu, Z., Zhang, Y., Yilmaz, T., Vescovo, E., Hashimoto, M., Lu, D., Yakobson, B. I., Dai, P., Chu, J., Si, Q., Yi, M. 2024

  View details for DOI 10.1038/s41567-023-02362-3

  View details for Web of Science ID 001150008400002

• Two-step electronic response to magnetic ordering in a van der Waals ferromagnet PHYSICAL REVIEW B Wu, H., Zhu, J., Chen, L., Butcher, M. W., Yue, Z., Yuan, D., He, Y., Oh, J., Gao, B., Huang, J., Wu, S., Gong, C., Guo, Y., Mo, S., Denlinger, J., Lu, D., Hashimoto, M., Stone, M. B., Kolesnikov, A. I., Chi, S., Kono, J., Nevidomskyy, A. H., Birgeneau, R. J., Dai, P., Yi, M. 2024; 109 (4)

  View details for DOI 10.1103/PhysRevB.109.045416

  View details for Web of Science ID 001173495200007

• Ideal weak topological insulator and protected helical saddle points PHYSICAL REVIEW B Oh, J., Xu, T., Dhale, N., Li, S., Lei, C., Yoon, C., Liu, W., Huang, J., Wu, H., Hashimoto, M., Lu, D., Jozwiak, C., Bostwick, A., Rotenberg, E., Lau, C., Lv, B., Zhang, F., Birgeneau, R. J., Yi, M. 2023; 108 (20)

  View details for DOI 10.1103/PhysRevB.108.L201104

  View details for Web of Science ID 001104468200001

• Discovery of Charge Order in the Transition Metal Dichalcogenide Fe_{x}NbS_{2}. Physical review letters Wu, S., Basak, R., Li, W., Kim, J., Ryan, P. J., Lu, D., Hashimoto, M., Nelson, C., Acevedo-Esteves, R., Haley, S. C., Analytis, J. G., He, Y., Frano, A., Birgeneau, R. J. 2023; 131 (18): 186701

  Abstract

  The Fe intercalated transition metal dichalcogenide (TMD), Fe_{1/3}NbS_{2}, exhibits remarkable resistance switching properties and highly tunable spin ordering phases due to magnetic defects. We conduct synchrotron x-ray scattering measurements on both underintercalated (x=0.32) and overintercalated (x=0.35) samples. We discover a new charge order phase in the overintercalated sample, where the excess Fe atoms lead to a zigzag antiferromagnetic order. The agreement between the charge and magnetic ordering temperatures, as well as their intensity relationship, suggests a strong magnetoelastic coupling as the mechanism for the charge ordering. Our results reveal the first example of a charge order phase among the intercalated TMD family and demonstrate the ability to stabilize charge modulation by introducing electronic correlations, where the charge order is absent in bulk 2H-NbS_{2} compared to other pristine TMDs.

  View details for DOI 10.1103/PhysRevLett.131.186701

  View details for PubMedID 37977621

• Tuning the band topology of GdSb by epitaxial strain APL MATERIALS Inbar, H. S., Ho, D. Q., Chatterjee, S., Engel, A. N., Khalid, S., Dempsey, C. P., Pendharkar, M., Chang, Y., Nishihaya, S., Fedorov, A. V., Lu, D., Hashimoto, M., Read, D., Janotti, A., Palmstrom, C. J. 2023; 11 (11)

  View details for DOI 10.1063/5.0155218

  View details for Web of Science ID 001123168300001

• Role of electron-phonon coupling in excitonic insulator candidate Ta2NiSe5 PHYSICAL REVIEW RESEARCH Chen, C., Chen, X., Tang, W., Li, Z., Wang, S., Ding, S., Kang, Z., Jozwiak, C., Bostwick, A., Rotenberg, E., Hashimoto, M., Lu, D., Ruff, J. C., Louie, S. G., Birgeneau, R. J., Chen, Y., Wang, Y., He, Y. 2023; 5 (4)

  View details for DOI 10.1103/PhysRevResearch.5.043089

  View details for Web of Science ID 001098159100001

• Potential Lifshitz transition at optimal substitution in nematic pnictide Ba1-xSrxNi2As2. Science advances Narayan, D. M., Hao, P., Kurleto, R., Berggren, B. S., Linn, A. G., Eckberg, C., Saraf, P., Collini, J., Zavalij, P., Hashimoto, M., Lu, D., Fernandes, R. M., Paglione, J., Dessau, D. S. 2023; 9 (42): eadi4966

  Abstract

  BaNi2As2 is a structural analog of the pnictide superconductor BaFe2As2, which, like the iron-based superconductors, hosts a variety of ordered phases including charge density waves (CDWs), electronic nematicity, and superconductivity. Upon isovalent Sr substitution on the Ba site, the charge and nematic orders are suppressed, followed by a sixfold enhancement of the superconducting transition temperature (Tc). To understand the mechanisms responsible for enhancement of Tc, we present high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements of the Ba1-xSrxNi2As2 series, which agree well with our density functional theory (DFT) calculations throughout the substitution range. Analysis of our ARPES-validated DFT results indicates a Lifshitz transition and reasonably nested electron and hole Fermi pockets near optimal substitution where Tc is maximum. These nested pockets host Ni dxz/dyz orbital compositions, which we associate with the enhancement of nematic fluctuations, revealing unexpected connections to the iron-pnictide superconductors. This gives credence to a scenario in which nematic fluctuations drive an enhanced Tc.

  View details for DOI 10.1126/sciadv.adi4966

  View details for PubMedID 37851807

• Charge order induced Dirac pockets in the nonsymmorphic crystal TaTe4 PHYSICAL REVIEW B Zhang, Y., Zhou, R., Wu, H., Oh, J., Li, S., Huang, J., Denlinger, J. D., Hashimoto, M., Lu, D., Mo, S., Kelly, K. F., Birgeneau, R. J., Lv, B., Li, G., Yi, M. 2023; 108 (15)

  View details for DOI 10.1103/PhysRevB.108.155121

  View details for Web of Science ID 001087458500002

• Weyl nodal ring states and Landau quantization with very large magnetoresistance in square-net magnet EuGa4. Nature communications Lei, S., Allen, K., Huang, J., Moya, J. M., Wu, T. C., Casas, B., Zhang, Y., Oh, J. S., Hashimoto, M., Lu, D., Denlinger, J., Jozwiak, C., Bostwick, A., Rotenberg, E., Balicas, L., Birgeneau, R., Foster, M. S., Yi, M., Sun, Y., Morosan, E. 2023; 14 (1): 5812

  Abstract

  Magnetic topological semimetals allow for an effective control of the topological electronic states by tuning the spin configuration. Among them, Weyl nodalline semimetals are thought to have the greatest tunability, yet they are the least studied experimentally due to the scarcity of material candidates. Here, using a combination of angle-resolved photoemission spectroscopy and quantum oscillation measurements, together with density functional theory calculations, we identify the square-net compound EuGa4 as a magnetic Weyl nodal ring semimetal, in which the line nodes form closed rings near the Fermi level. The Weyl nodal ring states show distinct Landau quantization with clear spin splitting upon application of a magnetic field. At 2 K in a field of 14 T, the transverse magnetoresistance of EuGa4 exceeds 200,000%, which is more than two orders of magnitude larger than that of other known magnetic topological semimetals. Our theoretical model suggests that the non-saturating magnetoresistance up to 40 T arises as a consequence of the nodal ring state.

  View details for DOI 10.1038/s41467-023-40767-z

  View details for PubMedID 37726328

• From Stoner to local moment magnetism in atomically thin Cr2Te3. Nature communications Zhong, Y., Peng, C., Huang, H., Guan, D., Hwang, J., Hsu, K. H., Hu, Y., Jia, C., Moritz, B., Lu, D., Lee, J. S., Jia, J. F., Devereaux, T. P., Mo, S. K., Shen, Z. X. 2023; 14 (1): 5340

  Abstract

  The field of two-dimensional (2D) ferromagnetism has been proliferating over the past few years, with ongoing interests in basic science and potential applications in spintronic technology. However, a high-resolution spectroscopic study of the 2D ferromagnet is still lacking due to the small size and air sensitivity of the exfoliated nanoflakes. Here, we report a thickness-dependent ferromagnetism in epitaxially grown Cr2Te3 thin films and investigate the evolution of the underlying electronic structure by synergistic angle-resolved photoemission spectroscopy, scanning tunneling microscopy, x-ray absorption spectroscopy, and first-principle calculations. A conspicuous ferromagnetic transition from Stoner to Heisenberg-type is directly observed in the atomically thin limit, indicating that dimensionality is a powerful tuning knob to manipulate the novel properties of 2D magnetism. Monolayer Cr2Te3 retains robust ferromagnetism, but with a suppressed Curie temperature, due to the drastic drop in the density of states near the Fermi level. Our results establish atomically thin Cr2Te3 as an excellent platform to explore the dual nature of localized and itinerant ferromagnetism in 2D magnets.

  View details for DOI 10.1038/s41467-023-40997-1

  View details for PubMedID 37660171

  View details for PubMedCentralID PMC10475109

• Spectral evidence for unidirectional charge density wave in detwinned BaNi 2 As 2 PHYSICAL REVIEW B Guo, Y., Klemm, M., Oh, J., Xie, Y., Lei, B., Moreschini, L., Chen, C., Yue, Z., Gorovikov, S., Pedersen, T., Michiardi, M., Zhdanovich, S., Damascelli, A., Denlinger, J., Hashimoto, M., Lu, D., Jozwiak, C., Bostwick, A., Rotenberg, E., Mo, S., Moore, R. G., Kono, J., Birgeneau, R. J., Singh, D. J., Dai, P., Yi, M. 2023; 108 (8)

  View details for DOI 10.1103/PhysRevB.108.L081104

  View details for Web of Science ID 001236679500001

• Tunable Van Hove Singularity without Structural Instability in Kagome Metal CsTi_{3}Bi_{5}. Physical review letters Liu, B., Kuang, M., Luo, Y., Li, Y., Hu, C., Liu, J., Xiao, Q., Zheng, X., Huai, L., Peng, S., Wei, Z., Shen, J., Wang, B., Miao, Y., Sun, X., Ou, Z., Cui, S., Sun, Z., Hashimoto, M., Lu, D., Jozwiak, C., Bostwick, A., Rotenberg, E., Moreschini, L., Lanzara, A., Wang, Y., Peng, Y., Yao, Y., Wang, Z., He, J. 2023; 131 (2): 026701

  Abstract

  In kagome metal CsV_{3}Sb_{5}, multiple intertwined orders are accompanied by both electronic and structural instabilities. These exotic orders have attracted much recent attention, but their origins remain elusive. The newly discovered CsTi_{3}Bi_{5} is a Ti-based kagome metal to parallel CsV_{3}Sb_{5}. Here, we report angle-resolved photoemission experiments and first-principles calculations on pristine and Cs-doped CsTi_{3}Bi_{5} samples. Our results reveal that the van Hove singularity (vHS) in CsTi_{3}Bi_{5} can be tuned in a large energy range without structural instability, different from that in CsV_{3}Sb_{5}. As such, CsTi_{3}Bi_{5} provides a complementary platform to disentangle and investigate the electronic instability with a tunable vHS in kagome metals.

  View details for DOI 10.1103/PhysRevLett.131.026701

  View details for PubMedID 37505968

• Kondo interaction in FeTe and its potential role in the magnetic order. Nature communications Kim, Y., Kim, M., Kim, D., Kim, M., Kim, M., Cheng, C., Choi, J., Jung, S., Lu, D., Kim, J. H., Cho, S., Song, D., Oh, D., Yu, L., Choi, Y. J., Kim, H., Han, J. H., Jo, Y., Shim, J. H., Seo, J., Huh, S., Kim, C. 2023; 14 (1): 4145

  Abstract

  Finding d-electron heavy fermion states has been an important topic as the diversity in d-electron materials can lead to many exotic Kondo effect-related phenomena or new states of matter such as correlation-driven topological Kondo insulator. Yet, obtaining direct spectroscopic evidence for a d-electron heavy fermion system has been elusive to date. Here, we report the observation of Kondo lattice behavior in an antiferromagnetic metal, FeTe, via angle-resolved photoemission spectroscopy, scanning tunneling spectroscopy and transport property measurements. The Kondo lattice behavior is represented by the emergence of a sharp quasiparticle and Fano-type tunneling spectra at low temperatures. The transport property measurements confirm the low-temperature Fermi liquid behavior and reveal successive coherent-incoherent crossover upon increasing temperature. We interpret the Kondo lattice behavior as a result of hybridization between localized Fe 3dxy and itinerant Te 5pz orbitals. Our observations strongly suggest unusual cooperation between Kondo lattice behavior and long-range magnetic order.

  View details for DOI 10.1038/s41467-023-39827-1

  View details for PubMedID 37438375

• A unique van Hove singularity in kagome superconductor CsV3-xTaxSb5 with enhanced superconductivity. Nature communications Luo, Y., Han, Y., Liu, J., Chen, H., Huang, Z., Huai, L., Li, H., Wang, B., Shen, J., Ding, S., Li, Z., Peng, S., Wei, Z., Miao, Y., Sun, X., Ou, Z., Xiang, Z., Hashimoto, M., Lu, D., Yao, Y., Yang, H., Chen, X., Gao, H., Qiao, Z., Wang, Z., He, J. 2023; 14 (1): 3819

  Abstract

  Van Hove singularity (VHS) has been considered as a driving source for unconventional superconductivity. A VHS in two-dimensional (2D) materials consists of a saddle point connecting electron-like and hole-like bands. In a rare case, when a VHS appears at Fermi level, both electron-like and hole-like conduction can coexist, giving rise to an enhanced density of states as well as an attractive component of Coulomb interaction for unconventional electronic pairing. However, this van Hove scenario is often destroyed by an incorrect chemical potential or competing instabilities. Here, by using angle-resolved photoemission measurements, we report the observation of a VHS perfectly aligned with the Fermi level in a kagome superconductor CsV3-xTaxSb5 (x~0.4), in which a record-high superconducting transition temperature is achieved among all the current variants of AV3Sb5 (A=Cs, Rb, K) at ambient pressure. Doping dependent measurements reveal the important role of van Hove scenario in boosting superconductivity, and spectroscopic-imaging scanning tunneling microscopy measurements indicate a distinct superconducting state in this system.

  View details for DOI 10.1038/s41467-023-39500-7

  View details for PubMedID 37369675

• Kramers nodal lines and Weyl fermions in SmAlSi COMMUNICATIONS PHYSICS Zhang, Y., Gao, Y., Gao, X., Lei, S., Ni, Z., Oh, J., Huang, J., Yue, Z., Zonno, M., Gorovikov, S., Hashimoto, M., Lu, D., Denlinger, J. D., Birgeneau, R. J., Kono, J., Wu, L., Law, K., Morosan, E., Yi, M. 2023; 6 (1)

  View details for DOI 10.1038/s42005-023-01257-2

  View details for Web of Science ID 001003992100002

• Magnetism and charge density wave order in kagome FeGe NATURE PHYSICS Teng, X., Oh, J., Tan, H., Chen, L., Huang, J., Gao, B., Yin, J., Chu, J., Hashimoto, M., Lu, D., Jozwiak, C., Bostwick, A., Rotenberg, E., Granroth, G. E., Yan, B., Birgeneau, R. J., Dai, P., Yi, M. 2023

  View details for DOI 10.1038/s41567-023-01985-w

  View details for Web of Science ID 000948647800001

• Topology Hierarchy of Transition Metal Dichalcogenides Built from Quantum Spin Hall Layers. Advanced materials (Deerfield Beach, Fla.) Xu, L., Li, Y., Fang, Y., Zheng, H., Shi, W., Chen, C., Pei, D., Lu, D., Hashimoto, M., Wang, M., Yang, L., Feng, X., Zhang, H., Huang, F., Xue, Q., He, K., Liu, Z., Chen, Y. 2023: e2300227

  Abstract

  The evolution of the physical properties of two-dimensional material from monolayer limit to the bulk reveals unique consequences from dimension confinement and provides a distinct tuning knob for applications. Monolayer 1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum spin Hall (QSH) states are ideal two-dimensional building blocks of various three-dimensional topological phases. However, the stacking geometry was previously limited to the bulk 1T'-WTe2 type. Here, we introduce the novel 2M-TMDs consisting of translationally stacked 1T'-monolayers as promising material platforms with tunable inverted bandgaps and interlayer coupling. By performing advanced polarization-dependent angle-resolved photoemission spectroscopy as well as first-principles calculations on the electronic structure of 2M-TMDs, we revealed a topology hierarchy: 2M-WSe2 , MoS2, and MoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong topological insulator (STI). Further demonstration of topological phase transitions by tunning interlayer distance indicates that band inversion amplitude and interlayer coupling jointly determine different topological states in 2M-TMDs. We propose that 2M-TMDs are parent compounds of various exotic phases including topological superconductors and promise great application potentials in quantum electronics due to their flexibility in patterning with two-dimensional materials. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/adma.202300227

  View details for PubMedID 36870326

• Epitaxial growth, magnetoresistance, and electronic band structure of GdSb magnetic semimetal films PHYSICAL REVIEW MATERIALS Inbar, H. S., Ho, D. Q., Chatterjee, S., Pendharkar, M., Engel, A. N., Dong, J. T., Khalid, S., Chang, Y., Guo, T., Fedorov, A., Lu, D., Hashimoto, M., Read, D., Janotti, A., Palmstrom, C. J. 2022; 6 (12)

  View details for DOI 10.1103/PhysRevMaterials.6.L121201

  View details for Web of Science ID 000898121500003

• Topological electronic structure evolution with symmetry-breaking spin reorientation in (Fe1-xCox)Sn PHYSICAL REVIEW B Moore, R. G., Okamoto, S., Li, H., Meier, W. R., Miao, H., Lee, H., Hashimoto, M., Lu, D., Dagotto, E., McGuire, M. A., Sales, B. C. 2022; 106 (11)

  View details for DOI 10.1103/PhysRevB.106.115141

  View details for Web of Science ID 000866512400001

• Uniaxial ferromagnetism in the kagome metal TbV6Sn6 PHYSICAL REVIEW B Rosenberg, E., DeStefano, J. M., Guo, Y., Oh, J., Hashimoto, M., Lu, D., Birgeneau, R. J., Lee, Y., Ke, L., Yi, M., Chu, J. 2022; 106 (11)

  View details for DOI 10.1103/PhysRevB.106.115139

  View details for Web of Science ID 000862965600002

• Discovery of charge density wave in a kagome lattice antiferromagnet. Nature Teng, X., Chen, L., Ye, F., Rosenberg, E., Liu, Z., Yin, J., Jiang, Y., Oh, J. S., Hasan, M. Z., Neubauer, K. J., Gao, B., Xie, Y., Hashimoto, M., Lu, D., Jozwiak, C., Bostwick, A., Rotenberg, E., Birgeneau, R. J., Chu, J., Yi, M., Dai, P. 2022; 609 (7927): 490-495

  Abstract

  A hallmark of strongly correlated quantum materials is the rich phase diagram resulting from competing and intertwined phases with nearly degenerate ground-state energies1,2. A well-known example is the copper oxides, in which a charge density wave (CDW) is ordered well above and strongly coupled to the magnetic order to form spin-charge-separated stripes that compete with superconductivity1,2. Recently, such rich phase diagrams have also been shown in correlated topological materials. In 2D kagome lattice metals consisting of corner-sharing triangles, the geometry of the lattice can produce flat bands with localized electrons3,4, non-trivial topology5-7, chiral magnetic order8,9, superconductivity and CDW order10-15. Although CDW has been found in weakly electron-correlated non-magnetic AV3Sb5 (A=K, Rb, Cs)10-15, it has not yet been observed in correlated magnetic-ordered kagome lattice metals4,16-21. Here we report the discovery of CDW in the antiferromagnetic (AFM) ordered phase of kagome lattice FeGe (refs.16-19). The CDW in FeGe occurs at wavevectors identical to that of AV3Sb5 (refs.10-15), enhances the AFM ordered moment and induces an emergent anomalous Hall effect22,23. Our findings suggest that CDW in FeGe arises from the combination of electron-correlations-driven AFM order and van Hove singularities (vHSs)-driven instability possibly associated with a chiral flux phase24-28, in stark contrast to strongly correlated copper oxides1,2 and nickelates29-31, in which the CDW precedes or accompanies the magnetic order.

  View details for DOI 10.1038/s41586-022-05034-z

  View details for PubMedID 36104552

• Differentiated roles of Lifshitz transition on thermodynamics and superconductivity in La2-xSrxCuO4. Proceedings of the National Academy of Sciences of the United States of America Zhong, Y., Chen, Z., Chen, S., Xu, K., Hashimoto, M., He, Y., Uchida, S., Lu, D., Mo, S., Shen, Z. 2022; 119 (32): e2204630119

  Abstract

  The effect of Lifshitz transition on thermodynamics and superconductivity in hole-doped cuprates has been heavily debated but remains an open question. In particular, an observed peak of electronic specific heat is proposed to originate from fluctuations of a putative quantum critical point p* (e.g., the termination of pseudogap at zero temperature), which is close to but distinguishable from the Lifshitz transition in overdoped La-based cuprates where the Fermi surface transforms from hole-like to electron-like. Here we report an in situ angle-resolved photoemission spectroscopy study of three-dimensional Fermi surfaces in La2-xSrxCuO4 thin films (x = 0.06 to 0.35). With accurate kz dispersion quantification, the said Lifshitz transition is determined to happen within a finite range around x = 0.21. Normal state electronic specific heat, calculated from spectroscopy-derived band parameters, reveals a doping-dependent profile with a maximum at x = 0.21 that agrees with previous thermodynamic microcalorimetry measurements. The account of the specific heat maximum by underlying band structures excludes the need for additionally dominant contribution from the quantum fluctuations at p*. A d-wave superconducting gap smoothly across the Lifshitz transition demonstrates the insensitivity of superconductivity to the dramatic density of states enhancement.

  View details for DOI 10.1073/pnas.2204630119

  View details for PubMedID 35914123

• Electronic states dressed by an out-of-plane supermodulation in the quasi-two-dimensional PHYSICAL REVIEW B Luo, Y., Peng, S., Teicher, S. L., Huai, L., Hu, Y., Han, Y., Ortiz, B. R., Liang, Z., Wei, Z., Shen, J., Ou, Z., Wang, B., Miao, Y., Guo, M., Hashimoto, M., Lu, D., Qiao, Z., Wang, Z., Wilson, S. D., Chen, X., He, J. 2022; 105 (24)

  View details for DOI 10.1103/PhysRevB.105.L241111

  View details for Web of Science ID 000823853600001

• Nematic Fluctuations in the Non-Superconducting Iron Pnictide BaFe1.9-xNi0.1CrxAs2 FRONTIERS IN PHYSICS Gong, D., Yi, M., Wang, M., Xie, T., Zhang, W., Danilkin, S., Deng, G., Liu, X., Park, J. T., Ikeuchi, K., Kamazawa, K., Mo, S., Hashimoto, M., Lu, D., Zhang, R., Dai, P., Birgeneau, R. J., Li, S., Luo, H. 2022; 10

  View details for DOI 10.3389/fphy.2022.886459

  View details for Web of Science ID 000816857200001

• Electronic nature of the pseudogap in electron-doped Sr2IrO4 NPJ QUANTUM MATERIALS Peng, S., Lane, C., Hu, Y., Guo, M., Chen, X., Sun, Z., Hashimoto, M., Lu, D., Shen, Z., Wu, T., Chen, X., Markiewicz, R. S., Wang, Y., Bansil, A., Wilson, S. D., He, J. 2022; 7 (1)

  View details for DOI 10.1038/s41535-022-00467-1

  View details for Web of Science ID 000805777800001

• Electronic structure of superconducting nickelates probed by resonant photoemission spectroscopy MATTER Chen, Z., Osada, M., Li, D., Been, E. M., Chen, S., Hashimoto, M., Lu, D., Mo, S., Lee, K., Wang, B., Rodolakis, F., McChesney, J. L., Jia, C., Moritz, B., Devereaux, T. P., Hwang, H. Y., Shen, Z. 2022; 5 (6)

  View details for DOI 10.1016/j.matt.2022.01.020

  View details for Web of Science ID 000810939100001

• Strain-controlled evolution of electronic structure indicating topological phase transition in the quasi-one-dimensional superconductor TaSe3 PHYSICAL REVIEW B Hyun, J., Jeong, M., Jung, M., Lee, Y., Kim, Y., Jung, S., Seok, B., Song, J., Lim, C., Cha, J., Lee, G., An, Y., Hashimoto, M., Lu, D., Denlinger, J. D., Kim, S., Kim, C., Han, M., Kim, S., Kim, Y. 2022; 105 (11)

  View details for DOI 10.1103/PhysRevB.105.115143

  View details for Web of Science ID 000800233300001

• Nonsymmorphic symmetry-protected band crossings in a square-net metal PtPb4 NPJ QUANTUM MATERIALS Wu, H., Hallas, A. M., Cai, X., Huang, J., Oh, J., Loganathan, V., Weiland, A., McCandless, G. T., Chan, J. Y., Mo, S., Lu, D., Hashimoto, M., Denlinger, J., Birgeneau, R. J., Nevidomskyy, A. H., Li, G., Morosan, E., Yi, M. 2022; 7 (1)

  View details for DOI 10.1038/s41535-022-00441-x

  View details for Web of Science ID 000770623900004

• Large anomalous Hall effect induced by weak ferromagnetism in the noncentrosymmetric antiferromagnet CoNb3S6 PHYSICAL REVIEW B Tanaka, H., Okazaki, S., Kuroda, K., Noguchi, R., Arai, Y., Minami, S., Ideta, S., Tanaka, K., Lu, D., Hashimoto, M., Kandyba, V., Cattelan, M., Barinov, A., Muro, T., Sasagawa, T., Kondo, T. 2022; 105 (12)

  View details for DOI 10.1103/PhysRevB.105.L121102

  View details for Web of Science ID 000766641900002

• Correlation-driven electronic reconstruction in FeTe1-xSex COMMUNICATIONS PHYSICS Huang, J., Yu, R., Xu, Z., Zhu, J., Oh, J., Jiang, Q., Wang, M., Wu, H., Chen, T., Denlinger, J. D., Mo, S., Hashimoto, M., Michiardi, M., Pedersen, T. M., Gorovikov, S., Zhdanovich, S., Damascelli, A., Gu, G., Dai, P., Chu, J., Lu, D., Si, Q., Birgeneau, R. J., Yi, M. 2022; 5 (1)

  View details for DOI 10.1038/s42005-022-00805-6

  View details for Web of Science ID 000747143700001

• Unconventional spectral signature of Tc in a pure d-wave superconductor. Nature Chen, S., Hashimoto, M., He, Y., Song, D., He, J., Li, Y., Ishida, S., Eisaki, H., Zaanen, J., Devereaux, T. P., Lee, D., Lu, D., Shen, Z. 1800; 601 (7894): 562-567

  Abstract

  In conventional superconductors, the phase transition into a zero-resistance and perfectly diamagnetic state is accompanied by a jump in the specific heat and the opening of a spectral gap1. In the high-transition-temperature (high-Tc) cuprates, although the transport, magnetic and thermodynamic signatures of Tc have been known since the 1980s2, the spectroscopic singularity associated with the transition remains unknown. Here we resolve this long-standing puzzle with a high-precision angle-resolved photoemission spectroscopy (ARPES) study on overdoped (Bi,Pb)2Sr2CaCu2O8+delta (Bi2212). We first probe the momentum-resolved electronic specific heat via spectroscopy and reproduce the specific heat peak at Tc, completing the missing link for a holistic description of superconductivity. Then, by studying the full momentum, energy and temperature evolution of the spectra, we reveal that this thermodynamic anomaly arises from the singular growth of in-gap spectral intensity across Tc. Furthermore, we observe that the temperature evolution of in-gap intensity is highly anisotropic in the momentum space, and the gap itself obeys both the d-wave functional form and particle-hole symmetry. These findings support the scenario that the superconducting transition is driven by phase fluctuations. They also serve as an anchor point for understanding the Fermi arc and pseudogap phenomena in underdoped cuprates.

  View details for DOI 10.1038/s41586-021-04251-2

  View details for PubMedID 35082417

• Unconventional Hysteretic Transition in a Charge Density Wave. Physical review letters Lv, B. Q., Zong, A., Wu, D., Rozhkov, A. V., Fine, B. V., Chen, S. D., Hashimoto, M., Lu, D. H., Li, M., Huang, Y. B., Ruff, J. P., Walko, D. A., Chen, Z. H., Hwang, I., Su, Y., Shen, X., Wang, X., Han, F., Po, H. C., Wang, Y., Jarillo-Herrero, P., Wang, X., Zhou, H., Sun, C. J., Wen, H., Shen, Z. X., Wang, N. L., Gedik, N. 2022; 128 (3): 036401

  Abstract

  Hysteresis underlies a large number of phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. Here, we report an unconventional hysteretic transition in a quasi-2D material, EuTe_{4}. By combining transport, photoemission, diffraction, and x-ray absorption measurements, we observe that the hysteresis loop has a temperature width of more than 400 K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge density wave (CDW) phase of EuTe_{4} with no change in the CDW modulation periodicity. We interpret the hysteresis as an unusual switching of the relative CDW phases in different layers, a phenomenon unique to quasi-2D compounds that is not present in either purely 2D or strongly coupled 3D systems. Our findings challenge the established theories on metastable states in density wave systems, pushing the boundary of understanding hysteretic transitions in a broken-symmetry state.

  View details for DOI 10.1103/PhysRevLett.128.036401

  View details for PubMedID 35119886

• Realizing Kagome Band Structure in Two-Dimensional Kagome Surface States of RV6Sn6 (R = Gd, Ho) PHYSICAL REVIEW LETTERS Peng, S., Han, Y., Pokharel, G., Shen, J., Li, Z., Hashimoto, M., Lu, D., Ortiz, B. R., Luo, Y., Li, H., Guo, M., Wang, B., Cui, S., Sun, Z., Qiao, Z., Wilson, S. D., He, J. 2021; 127 (26)

  View details for DOI 10.1103/PhysRevLett.127.266401

  View details for Web of Science ID 000735472500001

• Room-Temperature Topological Phase Transition in Quasi-One-Dimensional Material Bi4I4 PHYSICAL REVIEW X Huang, J., Li, S., Yoon, C., Oh, J., Wu, H., Liu, X., Dhale, N., Zhou, Y., Guo, Y., Zhang, Y., Hashimoto, M., Lu, D., Denlinger, J., Wang, X., Lau, C., Birgeneau, R. J., Zhang, F., Lv, B., Yi, M. 2021; 11 (3)

  View details for DOI 10.1103/PhysRevX.11.031042

  View details for Web of Science ID 000688547300001

• Author Correction: Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3. Nature materials Lin, C., Ochi, M., Noguchi, R., Kuroda, K., Sakoda, M., Nomura, A., Tsubota, M., Zhang, P., Bareille, C., Kurokawa, K., Arai, Y., Kawaguchi, K., Tanaka, H., Yaji, K., Harasawa, A., Hashimoto, M., Lu, D., Shin, S., Arita, R., Tanda, S., Kondo, T. 2021

  View details for DOI 10.1038/s41563-021-01056-6

  View details for PubMedID 34163046

• Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3. Nature materials Lin, C., Ochi, M., Noguchi, R., Kuroda, K., Sakoda, M., Nomura, A., Tsubota, M., Zhang, P., Bareille, C., Kurokawa, K., Arai, Y., Kawaguchi, K., Tanaka, H., Yaji, K., Harasawa, A., Hashimoto, M., Lu, D., Shin, S., Arita, R., Tanda, S., Kondo, T. 2021

  Abstract

  Control of the phase transition from topological to normal insulators can allow for an on/off switching of spin current. While topological phase transitions have been realized by elemental substitution in semiconducting alloys, such an approach requires preparation of materials with various compositions. Thus it is quite far from a feasible device application, which demands a reversible operation. Here we use angle-resolved photoemission spectroscopy and spin- and angle-resolved photoemission spectroscopy to visualize the strain-driven band-structure evolution of the quasi-one-dimensional superconductor TaSe3. We demonstrate that it undergoes reversible strain-induced topological phase transitions from a strong topological insulator phase with spin-polarized, quasi-one-dimensional topological surface states, to topologically trivial semimetal and band insulating phases. The quasi-one-dimensional superconductor TaSe3 provides a suitable platform for engineering the topological spintronics, for example as an on/off switch for a spin current that is robust against impurity scattering.

  View details for DOI 10.1038/s41563-021-01004-4

  View details for PubMedID 34017119

• Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Jia, T., Chen, Z., Rebec, S. N., Hashimoto, M., Lu, D., Devereaux, T. P., Lee, D. H., Moore, R. G., Shen, Z. X. 2021; 8 (9): 2003454

  Abstract

  The enhanced superconductivity in monolayer FeSe on titanates opens a fascinating pathway toward the rational design of high-temperature superconductors. Utilizing the state-of-the-art oxide plus chalcogenide molecular beam epitaxy systems in situ connected to a synchrotron angle-resolved photoemission spectroscope, epitaxial LaTiO3 layers with varied atomic thicknesses are inserted between monolayer FeSe and SrTiO3, for systematic modulation of interfacial chemical potential. With the dramatic increase of electron accumulation at the LaTiO3/SrTiO3 surface, providing a substantial surge of work function mismatch across the FeSe/oxide interface, the charge transfer and the superconducting gap in the monolayer FeSe are found to remain markedly robust. This unexpected finding indicate the existence of an intrinsically anchored "magic" doping within the monolayer FeSe systems.

  View details for DOI 10.1002/advs.202003454

  View details for PubMedID 33977049

  View details for PubMedCentralID PMC8097367

• Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates ADVANCED SCIENCE Jia, T., Chen, Z., Rebec, S. N., Hashimoto, M., Lu, D., Devereaux, T. P., Lee, D., Moore, R. G., Shen, Z. 2021

  View details for DOI 10.1002/advs.202003454

  View details for Web of Science ID 000617867700001

• Evidence for a higher-order topological insulator in a three-dimensional material built from van der Waals stacking of bismuth-halide chains. Nature materials Noguchi, R., Kobayashi, M., Jiang, Z., Kuroda, K., Takahashi, T., Xu, Z., Lee, D., Hirayama, M., Ochi, M., Shirasawa, T., Zhang, P., Lin, C., Bareille, C., Sakuragi, S., Tanaka, H., Kunisada, S., Kurokawa, K., Yaji, K., Harasawa, A., Kandyba, V., Giampietri, A., Barinov, A., Kim, T. K., Cacho, C., Hashimoto, M., Lu, D., Shin, S., Arita, R., Lai, K., Sasagawa, T., Kondo, T. 2021

  Abstract

  Low-dimensional van der Waals materials have been extensively studied as a platform with which to generate quantum effects. Advancing this research, topological quantum materials with van der Waals structures are currently receiving a great deal of attention. Here, we use the concept of designing topological materials by the van der Waals stacking of quantum spin Hall insulators. Most interestingly, we find that a slight shift of inversion centre in the unit cell caused by a modification of stacking induces a transition from a trivial insulator to a higher-order topological insulator. Based on this, we present angle-resolved photoemission spectroscopy results showing that the real three-dimensional material Bi4Br4 is a higher-order topological insulator. Our demonstration that various topological states can be selected by stacking chains differently, combined with the advantages of van der Waals materials, offers a playground for engineering topologically non-trivial edge states towards future spintronics applications.

  View details for DOI 10.1038/s41563-020-00871-7

  View details for PubMedID 33398124

• Anomalously strong near-neighbor attraction in doped 1D cuprate chains. Science (New York, N.Y.) Chen, Z., Wang, Y., Rebec, S. N., Jia, T., Hashimoto, M., Lu, D., Moritz, B., Moore, R. G., Devereaux, T. P., Shen, Z. 2021; 373 (6560): 1235-1239

  Abstract

  [Figure: see text].

  View details for DOI 10.1126/science.abf5174

  View details for PubMedID 34516788

• Observation of Topological Electronic Structure in Quasi-1D Superconductor TaSe3 MATTER Chen, C., Liang, A., Liu, S., Nie, S., Huang, J., Wang, M., Li, Y., Pei, D., Yang, H., Zheng, H., Zhang, Y., Lu, D., Hashimoto, M., Barinov, A., Jozwiak, C., Bostwick, A., Rotenberg, E., Kou, X., Yang, L., Guo, Y., Wang, Z., Yuan, H., Liu, Z., Chen, Y. 2020; 3 (6): 2055–65

  View details for DOI 10.1016/j.matt.2020.09.005

  View details for Web of Science ID 000598228500005

• Emergence of quasiparticles in a doped Mott insulator COMMUNICATIONS PHYSICS Wang, Y., He, Y., Wohlfeld, K., Hashimoto, M., Huang, E. W., Lu, D., Mo, S., Komiya, S., Jia, C., Moritz, B., Shen, Z., Devereaux, T. P. 2020; 3 (1)

  View details for DOI 10.1038/s42005-020-00480-5

  View details for Web of Science ID 000594380600003

• Electronic structure of the Si-containing topological Dirac semimetal CaAl2Si2 PHYSICAL REVIEW B Deng, T., Chen, C., Su, H., He, J., Liang, A., Cui, S., Yang, H., Wang, C., Huang, K., Jozwiak, C., Bostwick, A., Rotenberg, E., Lu, D., Hashimoto, M., Yang, L., Liu, Z., Guo, Y., Xu, G., Liu, Z., Chen, Y. 2020; 102 (4)

  View details for DOI 10.1103/PhysRevB.102.045106

  View details for Web of Science ID 000545541000007

• Metallic surface states in a correlated d-electron topological Kondo insulator candidate FeSb2. Proceedings of the National Academy of Sciences of the United States of America Xu, K., Chen, S., He, Y., He, J., Tang, S., Jia, C., Ma, E. Y., Mo, S., Lu, D., Hashimoto, M., Devereaux, T. P., Shen, Z. 2020

  Abstract

  The resistance of a conventional insulator diverges as temperature approaches zero. The peculiar low-temperature resistivity saturation in the 4f Kondo insulator (KI) SmB6 has spurred proposals of a correlation-driven topological Kondo insulator (TKI) with exotic ground states. However, the scarcity of model TKI material families leaves difficulties in disentangling key ingredients from irrelevant details. Here we use angle-resolved photoemission spectroscopy (ARPES) to study FeSb2, a correlated d-electron KI candidate that also exhibits a low-temperature resistivity saturation. On the (010) surface, we find a rich assemblage of metallic states with two-dimensional dispersion. Measurements of the bulk band structure reveal band renormalization, a large temperature-dependent band shift, and flat spectral features along certain high-symmetry directions, providing spectroscopic evidence for strong correlations. Our observations suggest that exotic insulating states resembling those in SmB6 and YbB12 may also exist in systems with d instead of f electrons.

  View details for DOI 10.1073/pnas.2002361117

  View details for PubMedID 32571928

• Fermi surface reconstruction in electron-doped cuprates without antiferromagnetic long-range order. Proceedings of the National Academy of Sciences of the United States of America He, J., Rotundu, C. R., Scheurer, M. S., He, Y., Hashimoto, M., Xu, K., Wang, Y., Huang, E. W., Jia, T., Chen, S., Moritz, B., Lu, D., Lee, Y. S., Devereaux, T. P., Shen, Z. 2019; 116 (9): 3449–53

  Abstract

  Fermi surface (FS) topology is a fundamental property of metals and superconductors. In electron-doped cuprate Nd2-x Ce x CuO4 (NCCO), an unexpected FS reconstruction has been observed in optimal- and overdoped regime (x = 0.15-0.17) by quantum oscillation measurements (QOM). This is all the more puzzling because neutron scattering suggests that the antiferromagnetic (AFM) long-range order, which is believed to reconstruct the FS, vanishes before x = 0.14. To reconcile the conflict, a widely discussed external magnetic-field-induced AFM long-range order in QOM explains the FS reconstruction as an extrinsic property. Here, we report angle-resolved photoemission (ARPES) evidence of FS reconstruction in optimal- and overdoped NCCO. The observed FSs are in quantitative agreement with QOM, suggesting an intrinsic FS reconstruction without field. This reconstructed FS, despite its importance as a basis to understand electron-doped cuprates, cannot be explained under the traditional scheme. Furthermore, the energy gap of the reconstruction decreases rapidly near x = 0.17 like an order parameter, echoing the quantum critical doping in transport. The totality of the data points to a mysterious order between x = 0.14 and 0.17, whose appearance favors the FS reconstruction and disappearance defines the quantum critical doping. A recent topological proposal provides an ansatz for its origin.

  View details for PubMedID 30808739

• Soft X-ray spectroscopy with transition-edge sensors at Stanford Synchrotron Radiation Lightsource beamline 10-1. The Review of scientific instruments Lee, S. J., Titus, C. J., Alonso Mori, R. n., Baker, M. L., Bennett, D. A., Cho, H. M., Doriese, W. B., Fowler, J. W., Gaffney, K. J., Gallo, A. n., Gard, J. D., Hilton, G. C., Jang, H. n., Joe, Y. I., Kenney, C. J., Knight, J. n., Kroll, T. n., Lee, J. S., Li, D. n., Lu, D. n., Marks, R. n., Minitti, M. P., Morgan, K. M., Ogasawara, H. n., O'Neil, G. C., Reintsema, C. D., Schmidt, D. R., Sokaras, D. n., Ullom, J. N., Weng, T. C., Williams, C. n., Young, B. A., Swetz, D. S., Irwin, K. D., Nordlund, D. n. 2019; 90 (11): 113101

  Abstract

  We present results obtained with a new soft X-ray spectrometer based on transition-edge sensors (TESs) composed of Mo/Cu bilayers coupled to bismuth absorbers. This spectrometer simultaneously provides excellent energy resolution, high detection efficiency, and broadband spectral coverage. The new spectrometer is optimized for incident X-ray energies below 2 keV. Each pixel serves as both a highly sensitive calorimeter and an X-ray absorber with near unity quantum efficiency. We have commissioned this 240-pixel TES spectrometer at the Stanford Synchrotron Radiation Lightsource beamline 10-1 (BL 10-1) and used it to probe the local electronic structure of sample materials with unprecedented sensitivity in the soft X-ray regime. As mounted, the TES spectrometer has a maximum detection solid angle of 2 × 10-3 sr. The energy resolution of all pixels combined is 1.5 eV full width at half maximum at 500 eV. We describe the performance of the TES spectrometer in terms of its energy resolution and count-rate capability and demonstrate its utility as a high throughput detector for synchrotron-based X-ray spectroscopy. Results from initial X-ray emission spectroscopy and resonant inelastic X-ray scattering experiments obtained with the spectrometer are presented.

  View details for DOI 10.1063/1.5119155

  View details for PubMedID 31779391

• Incoherent strange metal sharply bounded by a critical doping in Bi2212. Science (New York, N.Y.) Chen, S. D., Hashimoto, M. n., He, Y. n., Song, D. n., Xu, K. J., He, J. F., Devereaux, T. P., Eisaki, H. n., Lu, D. H., Zaanen, J. n., Shen, Z. X. 2019; 366 (6469): 1099–1102

  Abstract

  In normal metals, macroscopic properties are understood using the concept of quasiparticles. In the cuprate high-temperature superconductors, the metallic state above the highest transition temperature is anomalous and is known as the "strange metal." We studied this state using angle-resolved photoemission spectroscopy. With increasing doping across a temperature-independent critical value pc ~ 0.19, we observed that near the Brillouin zone boundary, the strange metal, characterized by an incoherent spectral function, abruptly reconstructs into a more conventional metal with quasiparticles. Above the temperature of superconducting fluctuations, we found that the pseudogap also discontinuously collapses at the very same value of pc These observations suggest that the incoherent strange metal is a distinct state and a prerequisite for the pseudogap; such findings are incompatible with existing pseudogap quantum critical point scenarios.

  View details for DOI 10.1126/science.aaw8850

  View details for PubMedID 31780552

• Dichotomy of the photo-induced 2-dimensional electron gas on SrTiO3 surface terminations. Proceedings of the National Academy of Sciences of the United States of America Rebec, S. N., Jia, T. n., Sohail, H. M., Hashimoto, M. n., Lu, D. n., Shen, Z. X., Moore, R. G. 2019

  Abstract

  Oxide materials are important candidates for the next generation of electronics due to a wide array of desired properties, which they can exhibit alone or when combined with other materials. While SrTiO3 (STO) is often considered a prototypical oxide, it, too, hosts a wide array of unusual properties, including a 2-dimensional electron gas (2DEG), which can form at the surface when exposed to ultraviolet (UV) light. Using layer-by-layer growth of high-quality STO films, we show that the 2DEG only forms with the SrO termination and not with the TiO2 termination, contrary to expectation. This dichotomy of the observed angle-resolved photoemission spectroscopy (ARPES) spectra is similarly seen in BaTiO3 (BTO), in which the 2DEG is only observed for BaO-terminated films. These results will allow for a deeper understanding and better control of the electronic structure of titanate films, substrates, and heterostructures.

  View details for DOI 10.1073/pnas.1821937116

  View details for PubMedID 31391304

• Epitaxial growth of TiSe2/TiO2 heterostructure 2D MATERIALS Jia, T., Rebec, S. N., Tang, S., Xu, K., Sohail, H. M., Hashimoto, M., Lu, D., Moore, R. G., Shen, Z. 2019; 6 (1)

  View details for DOI 10.1088/2053-1583/aaeadf

  View details for Web of Science ID 000451023100001

• Phase transition and electronic structure evolution of MoTe2 induced by W substitution PHYSICAL REVIEW B Jin, W., Schiros, T., Lin, Y., Ma, J., Lou, R., Dai, Z., Yu, J., Rhodes, D., Sadowski, J. T., Tong, X., Qian, T., Hashimoto, M., Lu, D., Dadap, J. I., Wang, S., Santos, E. G., Zang, J., Pohl, K., Ding, H., Hone, J., Balicas, L., Pasupathy, A. N., Osgood, R. M. 2018; 98 (14)

  View details for DOI 10.1103/PhysRevB.98.144114

  View details for Web of Science ID 000448912000002

• Electronic structure of monolayer 1T'-MoTe2 grown by molecular beam epitaxy APL MATERIALS Tang, S., Zhang, C., Jia, C., Ryu, H., Hwang, C., Hashimoto, M., Lu, D., Liu, Z., Devereaux, T. P., Shen, Z., Mo, S. 2018; 6 (2)

  View details for DOI 10.1063/1.5004700

  View details for Web of Science ID 000426999900008

• Role of the orbital degree of freedom in iron-based superconductors NPJ QUANTUM MATERIALS Yi, M., Zhang, Y., Shen, Z., Lu, D. 2017; 2

  View details for DOI 10.1038/s41535-017-0059-y

  View details for Web of Science ID 000414584500001

• Large thermopower from dressed quasiparticles in the layered cobaltates and rhodates PHYSICAL REVIEW B Chen, S., He, Y., Zong, A., Zhang, Y., Hashimoto, M., Zhang, B., Yao, S., Chen, Y., Zhou, J., Chen, Y., Mo, S., Hussain, Z., Lu, D., Shen, Z. 2017; 96 (8)

  View details for DOI 10.1103/PhysRevB.96.081109

  View details for Web of Science ID 000407550400001

• Quantum spin Hall state in monolayer 1T '-WTe2 NATURE PHYSICS Tang, S., Zhang, C., Wong, D., Pedramrazi, Z., Tsai, H., Jia, C., Moritz, B., Claassen, M., Ryu, H., Kahn, S., Jiang, J., Yan, H., Hashimoto, M., Lu, D., Moore, R. G., Hwang, C., Hwang, C., Hussain, Z., Chen, Y., Ugeda, M. M., Liu, Z., Xie, X., Devereaux, T. P., Crommie, M. F., Mo, S., Shen, Z. 2017; 13 (7): 683-+

  View details for DOI 10.1038/NPHYS4174

  View details for Web of Science ID 000404629900018

• Ubiquitous strong electron-phonon coupling at the interface of FeSe/SrTiO3 NATURE COMMUNICATIONS Zhang, C., Liu, Z., Chen, Z., Xie, Y., He, R., Tang, S., He, J., Li, W., Jia, T., Rebec, S. N., Ma, E. Y., Yan, H., Hashimoto, M., Lu, D., Mo, S., Hikita, Y., Moore, R. G., Hwang, H. Y., Lee, D., Shen, Z. 2017; 8

  Abstract

  The observation of replica bands in single-unit-cell FeSe on SrTiO3 (STO)(001) by angle-resolved photoemission spectroscopy (ARPES) has led to the conjecture that the coupling between FeSe electrons and the STO phonons are responsible for the enhancement of Tc over other FeSe-based superconductors. However the recent observation of a similar superconducting gap in single-unit-cell FeSe/STO(110) raised the question of whether a similar mechanism applies. Here we report the ARPES study of the electronic structure of FeSe/STO(110). Similar to the results in FeSe/STO(001), clear replica bands are observed. We also present a comparative study of STO(001) and STO(110) bare surfaces, and observe similar replica bands separated by approximately the same energy, indicating this coupling is a generic feature of the STO surfaces and interfaces. Our findings suggest that the large superconducting gaps observed in FeSe films grown on different STO surface terminations are likely enhanced by a common mechanism.

  View details for DOI 10.1038/ncomms14468

  View details for Web of Science ID 000393739700001

  View details for PubMedCentralID PMC5311057

• . Nature communications Zhang, C., Liu, Z., Chen, Z., Xie, Y., He, R., Tang, S., He, J., Li, W., Jia, T., Rebec, S. N., Ma, E. Y., Yan, H., Hashimoto, M., Lu, D., Mo, S., Hikita, Y., Moore, R. G., Hwang, H. Y., Lee, D., Shen, Z. 2017; 8: 14468-?

  Abstract

  The observation of replica bands in single-unit-cell FeSe on SrTiO3 (STO)(001) by angle-resolved photoemission spectroscopy (ARPES) has led to the conjecture that the coupling between FeSe electrons and the STO phonons are responsible for the enhancement of Tc over other FeSe-based superconductors. However the recent observation of a similar superconducting gap in single-unit-cell FeSe/STO(110) raised the question of whether a similar mechanism applies. Here we report the ARPES study of the electronic structure of FeSe/STO(110). Similar to the results in FeSe/STO(001), clear replica bands are observed. We also present a comparative study of STO(001) and STO(110) bare surfaces, and observe similar replica bands separated by approximately the same energy, indicating this coupling is a generic feature of the STO surfaces and interfaces. Our findings suggest that the large superconducting gaps observed in FeSe films grown on different STO surface terminations are likely enhanced by a common mechanism.

  View details for DOI 10.1038/ncomms14468

  View details for PubMedID 28186084

• Direct spectroscopic evidence for phase competition between the pseudogap and superconductivity in Bi2Sr2CaCu2O8+delta NATURE MATERIALS Hashimoto, M., Nowadnick, E. A., He, R., Vishik, I. M., Moritz, B., He, Y., Tanaka, K., Moore, R. G., Lu, D., Yoshida, Y., Ishikado, M., Sasagawa, T., Fujita, K., Ishida, S., Uchida, S., Eisaki, H., Hussain, Z., Devereaux, T. P., Shen, Z. 2015; 14 (1): 37-42

  Abstract

  In the high-temperature (Tc) cuprate superconductors, a growing body of evidence suggests that the pseudogap phase, existing below the pseudogap temperature T(∗), is characterized by some broken electronic symmetries distinct from those associated with superconductivity. In particular, recent scattering experiments have suggested that charge ordering competes with superconductivity. However, no direct link of an interplay between the two phases has been identified from the important low-energy excitations. Here, we report an antagonistic singularity at Tc in the spectral weight of Bi2Sr2CaCu2O8+δ as compelling evidence for phase competition, which persists up to a high hole concentration p ~ 0.22. Comparison with theoretical calculations confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. The observation of the spectroscopic singularity at finite temperatures over a wide doping range provides new insights into the nature of the competitive interplay between the two orders and the complex phase diagram near the pseudogap critical point.

  View details for DOI 10.1038/NMAT4116

  View details for Web of Science ID 000346430100011

  View details for PubMedID 25362356

• Orbital character and electron correlation effects on two- and three-dimensional Fermi surfaces in KFe2As2 revealed by angle-resolved photoemission spectroscopy FRONTIERS IN PHYSICS Yoshida, T., Ideta, S., Nishi, I., Fujimori, A., Yi, M., Moore, R. G., Mo, S., Lu, D., Shen, Z., Hussain, Z., Kihou, K., Shirage, P. M., Kito, H., Lee, C., Iyo, A., Eisaki, H., Harima, H. 2014; 2

  View details for DOI 10.3389/fphy.2014.00017

  View details for Web of Science ID 000215935000017

• Phase competition in trisected superconducting dome PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Vishik, I. M., Hashimoto, M., He, R., LeeB, W., Schmitt, F., Lu, D., Moore, R. G., Zhang, C., Meevasana, W., Sasagawa, T., Uchida, S., Fujita, K., Ishida, S., Ishikado, M., Yoshida, Y., Eisaki, H., Hussain, Z., Devereaux, T. P., Shen, Z. 2012; 109 (45): 18332-18337

  Abstract

  A detailed phenomenology of low energy excitations is a crucial starting point for microscopic understanding of complex materials, such as the cuprate high-temperature superconductors. Because of its unique momentum-space discrimination, angle-resolved photoemission spectroscopy (ARPES) is ideally suited for this task in the cuprates, where emergent phases, particularly superconductivity and the pseudogap, have anisotropic gap structure in momentum space. We present a comprehensive doping- and temperature-dependence ARPES study of spectral gaps in Bi(2)Sr(2)CaCu(2)O(8+δ), covering much of the superconducting portion of the phase diagram. In the ground state, abrupt changes in near-nodal gap phenomenology give spectroscopic evidence for two potential quantum critical points, p = 0.19 for the pseudogap phase and p = 0.076 for another competing phase. Temperature dependence reveals that the pseudogap is not static below T(c) and exists p > 0.19 at higher temperatures. Our data imply a revised phase diagram that reconciles conflicting reports about the endpoint of the pseudogap in the literature, incorporates phase competition between the superconducting gap and pseudogap, and highlights distinct physics at the edge of the superconducting dome.

  View details for DOI 10.1073/pnas.1209471109

  View details for Web of Science ID 000311156700031

  View details for PubMedID 23093670

  View details for PubMedCentralID PMC3494935

• Angle-Resolved Photoemission Studies of Quantum Materials ANNUAL REVIEW OF CONDENSED MATTER PHYSICS, VOL 3 Lu, D., Vishik, I. M., Yi, M., Chen, Y., Moore, R. G., Shen, Z. 2012; 3: 129-167

  View details for DOI 10.1146/annurev-conmatphys-020911-125027

  View details for Web of Science ID 000301793100008

• Symmetry-breaking orbital anisotropy observed for detwinned Ba(Fe1-xCox)(2)As-2 above the spin density wave transition PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Yi, M., Lu, D., Chu, J., Analytis, J. G., Sorini, A. P., Kemper, A. F., Moritz, B., Mo, S., Moore, R. G., Hashimoto, M., Lee, W., Hussain, Z., Devereaux, T. P., Fisher, I. R., Shen, Z. 2011; 108 (17): 6878-6883

  View details for DOI 10.1073/pnas.1015572108

  View details for Web of Science ID 000289888500040

• Particle-hole symmetry breaking in the pseudogap state of Bi2201 NATURE PHYSICS Hashimoto, M., He, R., Tanaka, K., Testaud, J., Meevasana, W., Moore, R. G., Lu, D., Yao, H., Yoshida, Y., Eisaki, H., Devereaux, T. P., Hussain, Z., Shen, Z. 2010; 6 (6): 414-418

  View details for DOI 10.1038/NPHYS1632

  View details for Web of Science ID 000279014400011

• Anomalous Fermi-surface dependent pairing in a self-doped high-T-c superconductor PHYSICAL REVIEW LETTERS Chen, Y., Iyo, A., Yang, W., Zhou, X., Lu, D., Eisaki, H., Devereaux, T. P., Hussain, Z., Shen, Z. 2006; 97 (23)

  Abstract

  We report the discovery of a self-doped multilayer high Tc superconductor Ba2Ca3Cu4O8F2 (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi-surface sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a Tc of 60 K, possessing simultaneously both electron- and hole-doped Fermi-surface sheets. Intriguingly, the Fermi-surface sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic (pi/a, pi/a) scattering.

  View details for DOI 10.1103/PhysRevLett.97.236401

  View details for Web of Science ID 000242708900037

  View details for PubMedID 17280217