Simin Nie

All Publications

• Interwoven magnetic kagome metal overcomes geometric frustration. Nature materials Cheng, E., Wang, K., Hao, Y., Chen, W., Tan, H., Li, Z., Wang, M., Gao, W., Wu, D., Sun, S., Ying, T., Nie, S., Li, Y., Schnelle, W., Chen, H., Zhou, X., Koban, R., Chen, Y., Yan, B., Yang, Y. F., Wu, W., Liu, Z., Felser, C. 2025

  Abstract

  Magnetic kagome materials provide a platform for exploring magneto-transport phenomena, symmetry breaking and charge ordering driven by the intricate interplay among electronic structure, topology and magnetism. Yet geometric frustration in conventional kagome magnets limits their tunability. Here we propose a design strategy for interweaving quasi-one-dimensional magnetic Tb zigzag chains with non-magnetic Ti-based kagome bilayers in TbTi3Bi4. Comprehensive spectroscopic analyses reveal coexisting elliptical-spiral magnetic and spin-density-wave orders accompanied by a large ~90 meV band-folding gap. The combined magnetic and electronic state leads to a giant anomalous Hall conductivity of 105 Ω-1 cm-1, which exceeds that observed in frustrated kagome analogues. These results establish TbTi3Bi4 as a model system of magnetic kagome metals with strong electron-magnetism interactions and underscore the necessity of interweaving designed magnetic and charge layers separately to achieve tunable transport properties. This design strategy will enable the discovery of emergent quantum states and next-generation electronic materials.

  View details for DOI 10.1038/s41563-025-02414-4

  View details for PubMedID 41430496

  View details for PubMedCentralID 6217931

• Modulating superconductivity in elementary materials by doping. Scientific reports Nie, S., Zhang, X., Guo, J., Prinz, F. B. 2025; 15 (1): 43911

  Abstract

  Influenced by the discovery of high-temperature superconductivity in compressed hydrides, the search for superconductors with high transition temperatures has received growing attention. Here, based on first-principles calculations, the influence of doping on superconducting properties of five elementary materials (i.e., Mo, Nb, Pb, Al, Zr) is studied. The electron-phonon coupling strength and transition temperature can always be effectively increased due to both phonon softening and increased contribution of some specific phonons either by electron doping or hole doping. For each material, there is an optimum doping level with highest transition temperature. Our work highlights the crucial role of doping in raising the transition temperature of traditional Bardeen-Cooper-Schrieffer superconductors.

  View details for DOI 10.1038/s41598-025-27741-z

  View details for PubMedID 41402341

  View details for PubMedCentralID 2531064

• Mixed Conducting Oxide Coating for Lithium Batteries. ACS nano Jung, Y., Mueller, J. E., Chaikasetsin, S., Han, G. D., Nie, S., Han, H. S., Gür, T. M., Prinz, F. B. 2024

  Abstract

  Thin, uniform, and conformal coatings on the active electrode materials are gaining more importance to mitigate degradation mechanisms in lithium-ion batteries. To avoid polarization of the electrode, mixed conductors are of crucial importance. Atomic layer deposition (ALD) is employed in this work to provide superior uniformity, conformality, and the ability to precisely control the stoichiometry and thickness of the desired coating materials. We provide experimental and computational guidelines for the need of mixed electronic and ionic conducting coating materials, especially in the case where highly uniform and conformal coatings are achieved. We report promising results for ALD-deposited protective films achieved by doping fluorine (F) into a lithium vanadate coating. The F-doped lithium vanadate coating at the optimal doping level exhibits an electrical conductivity of 1.2 × 10-5 S·cm-1. Density functional theory calculations corroborate enhanced mixed electronic and ionic conduction in F-doped lithium vanadate through band structure analysis and climbing-image nudge elastic band (CI-NEB) calculations. It has been demonstrated that the experimentally determined optimal doping concentration aligns well with that predicted by density functional theory calculations. CI-NEB calculations have shown that the activation energy for lithium-ion transport was the lowest for optimally doped lithium vanadate.

  View details for DOI 10.1021/acsnano.4c16117

  View details for PubMedID 39700055

• Tunable Dirac semimetals with higher-order Fermi arcs in Kagome lattices Pd3Pb2X2 (X = S, Se) SCIENCE BULLETIN Nie, S., Chen, J., Yue, C., Le, C., Yuan, D., Wang, Z., Zhang, W., Weng, H. 2022; 67 (19): 1958-1961

  View details for DOI 10.1016/j.scib.2022.09.003

  View details for Web of Science ID 000875704200011

• Tunable Dirac semimetals with higher-order Fermi arcs in Kagome lattices Pd3Pb2X2 (X=S,Se). Science bulletin Nie, S., Chen, J., Yue, C., Le, C., Yuan, D., Wang, Z., Zhang, W., Weng, H. 2022; 67 (19): 1958-1961

  View details for DOI 10.1016/j.scib.2022.09.003

  View details for PubMedID 36546204

• Spontaneous Ferromagnetism Induced Topological Transition in EuB_{6}. Physical review letters Liu, W. L., Zhang, X., Nie, S. M., Liu, Z. T., Sun, X. Y., Wang, H. Y., Ding, J. Y., Jiang, Q., Sun, L., Xue, F. H., Huang, Z., Su, H., Yang, Y. C., Jiang, Z. C., Lu, X. L., Yuan, J., Cho, S., Liu, J. S., Liu, Z. H., Ye, M., Zhang, S. L., Weng, H. M., Liu, Z., Guo, Y. F., Wang, Z. J., Shen, D. W. 2022; 129 (16): 166402

  Abstract

  The interplay between various symmetries and electronic bands topology is one of the core issues for topological quantum materials. Spontaneous magnetism, which leads to the breaking of time-reversal symmetry, has been proven to be a powerful approach to trigger various exotic topological phases. In this Letter, utilizing the combination of angle-resolved photoemission spectroscopy, magneto-optical Kerr effect microscopy, and first-principles calculations, we present the direct evidence on the realization of the long-sought spontaneous ferromagnetism induced topological transition in soft ferromagnetic EuB_{6}. Explicitly, we reveal the topological transition is from Z_{2}=1 topological insulator in paramagnetic state to χ=1 magnetic topological semimetal in low temperature ferromagnetic state. Our results demonstrate that the simple band structure near the Fermi level and rich topological phases make EuB_{6} an ideal platform to study the topological phase physics.

  View details for DOI 10.1103/PhysRevLett.129.166402

  View details for PubMedID 36306743

• Magnetic Weyl Semimetal in K_{2}Mn_{3}(AsO_{4})_{3} with the Minimum Number of Weyl Points. Physical review letters Nie, S., Hashimoto, T., Prinz, F. B. 2022; 128 (17): 176401

  Abstract

  The "hydrogen atom" of magnetic Weyl semimetals, with the minimum number of Weyl points, has received growing attention recently due to the possible presence of Weyl-related phenomena. Here, we report a nontrivial electronic structure of the ferromagnetic alluaudite-type compound K_{2}Mn_{3}(AsO_{4})_{3}. Itexhibits only a pair of Weyl points constrained in the z direction by the twofold rotation symmetry, leading to extremely long Fermi arc surface states. In addition, the study of its low-energy effective model results in the discovery of various topological superconducting states, such as the hydrogen atom of a Weyl superconductor. Our Letter provides a feasible platform to explore the intrinsic properties related to Weyl points, and the related device applications.

  View details for DOI 10.1103/PhysRevLett.128.176401

  View details for PubMedID 35570444

• Multiple mobile excitons manifested as sidebands in quasi-one-dimensional metallic TaSe3. Nature materials Ma, J., Nie, S., Gui, X., Naamneh, M., Jandke, J., Xi, C., Zhang, J., Shang, T., Xiong, Y., Kapon, I., Kumar, N., Soh, Y., Gosalbez-Martinez, D., Yazyev, O. V., Fan, W., Hubener, H., Giovannini, U. D., Plumb, N. C., Radovic, M., Sentef, M. A., Xie, W., Wang, Z., Mudry, C., Muller, M., Shi, M. 2022

  Abstract

  Charge neutrality and their expected itinerant nature makes excitons potential transmitters of information. However, exciton mobility remains inaccessible to traditional optical experiments that only create and detect excitons with negligible momentum. Here, using angle-resolved photoemission spectroscopy, we detect dispersing excitons in the quasi-one-dimensional metallic trichalcogenide, TaSe3. The low density of conduction electrons and the low dimensionality in TaSe3 combined with a polaronic renormalization of the conduction band and the poorly screened interaction between these polarons and photo-induced valence holes leads to various excitonic bound states that we interpret as intrachain and interchain excitons, and possibly trions. The thresholds for the formation of a photo-hole together with an exciton appear as side valence bands with dispersions nearly parallel to the main valence band, but shifted to lower excitation energies. The energy separation between side and main valence bands can be controlled by surface doping, enabling the tuning of certain exciton properties.

  View details for DOI 10.1038/s41563-022-01201-9

  View details for PubMedID 35190656

• Observation of topological edge states in the quantum spin Hall insulator Ta2Pd3Te5 PHYSICAL REVIEW B Wang, X., Geng, D., Yan, D., Hu, W., Zhang, H., Yue, S., Sun, Z., Kumar, S., Schwier, E. F., Shimada, K., Cheng, P., Chen, L., Nie, S., Wang, Z., Shi, Y., Zhang, Y., Wu, K., Feng, B. 2021; 104 (24)

  View details for DOI 10.1103/PhysRevB.104.L241408

  View details for Web of Science ID 000924305000008

• Observation of electronic structure and electron-boson coupling in the low-dimensional superconductor Ta4Pd3Te16 PHYSICAL REVIEW B Yang, H. F., Liu, X. L., Nie, S. M., Shi, W. J., Huang, K., Zheng, H. J., Zhang, J., Li, Y. W., Liang, A. J., Wang, M. X., Yang, L. X., Guo, Y. F., Liu, Z. K., Chen, Y. L. 2021; 104 (22)

  View details for DOI 10.1103/PhysRevB.104.L220501

  View details for Web of Science ID 000726641900001

• Measurement of Superconductivity and Edge States in Topological Superconductor Candidate TaSe3 CHINESE PHYSICS LETTERS Liu, S., Nie, S., Qi, Y., Guo, Y., Yuan, H., Yang, L., Chen, Y., Wang, M., Liu, Z. 2021; 38 (7)

  View details for DOI 10.1088/0256-307X/38/7/077302

  View details for Web of Science ID 000681454600001

• Application of topological quantum chemistry in electrides PHYSICAL REVIEW B Nie, S., Qian, Y., Gao, J., Fang, Z., Weng, H., Wang, Z. 2021; 103 (20)

  View details for DOI 10.1103/PhysRevB.103.205133

  View details for Web of Science ID 000655884000003

• Time-Reversal Symmetry Breaking Driven Topological Phase Transition in EuB6 PHYSICAL REVIEW X Gao, S., Xu, S., Li, H., Yi, C., Nie, S., Rao, Z., Wang, H., Hu, Q., Chen, X., Fan, W., Huang, J., Huang, Y., Pryds, N., Shi, M., Wang, Z., Shi, Y., Xia, T., Qian, T., Ding, H. 2021; 11 (2)

  View details for DOI 10.1103/PhysRevX.11.021016

  View details for Web of Science ID 000643595400001

• High-throughput screening for Weyl semimetals with S4 symmetry SCIENCE BULLETIN Gao, J., Qian, Y., Nie, S., Fang, Z., Weng, H., Wang, Z. 2021; 66 (7): 667–75

  View details for DOI 10.1016/j.scib.2020.12.028

  View details for Web of Science ID 000635050500011

• High-throughput screening for Weyl semimetals with S4 symmetry. Science bulletin Gao, J., Qian, Y., Nie, S., Fang, Z., Weng, H., Wang, Z. 2021; 66 (7): 667-675

  Abstract

  Based on irreducible representations (or symmetry eigenvalues) and compatibility relations (CR), a material can be predicted to be a topological/trivial insulator (satisfying CR) or a topological semimetal (violating CR). However, Weyl semimetals (WSMs) usually go beyond this symmetry-based strategy. In other words, Weyl nodes could emerge in a material, no matter if its occupied bands satisfy CR, or if the symmetry indicators are zero. In this work, we propose a new topological invariant χ for the systems with S4 symmetry (i.e., the improper rotation S4(≡IC4z) is a proper fourfold rotation (C4z) followed by inversion (I)), which can be used to diagnose the WSM phase. Moreover, χ can be easily computed through the one-dimensional Wilson-loop technique. By applying this method to the high-throughput screening in our first-principles calculations, we predict a lot of WSMs in both nonmagnetic and magnetic compounds. Various interesting properties (e.g., magnetic frustration effects, superconductivity and spin-glass order, etc.) are found in predicted WSMs, which provide realistic platforms for future experimental study of the interplay between Weyl fermions and other exotic states.

  View details for DOI 10.1016/j.scib.2020.12.028

  View details for PubMedID 36654442

• Discovery of [Formula: see text] rotation anomaly in topological crystalline insulator SrPb. Nature communications Fan, W., Nie, S., Wang, C., Fu, B., Yi, C., Gao, S., Rao, Z., Yan, D., Ma, J., Shi, M., Huang, Y., Shi, Y., Wang, Z., Qian, T., Ding, H. 2021; 12 (1): 2052

  Abstract

  Topological crystalline insulators (TCIs) are insulating electronic states with nontrivial topology protected by crystalline symmetries. Recently, theory has proposed new classes of TCIs protected by rotation symmetries [Formula: see text], which have surface rotation anomaly evading the fermion doubling theorem, i.e., n instead of 2n Dirac cones on the surface preserving the rotation symmetry. Here, we report the first realization of the [Formula: see text] rotation anomaly in a binary compound SrPb. Our first-principles calculations reveal two massless Dirac fermions protected by the combination of time-reversal symmetry [Formula: see text] and [Formula: see text] on the (010) surface. Using angle-resolved photoemission spectroscopy, we identify two Dirac surface states inside the bulk band gap of SrPb, confirming the [Formula: see text] rotation anomaly in the new classes of TCIs. The findings enrich the classification of topological phases, which pave the way for exploring exotic behavior of the new classes of TCIs.

  View details for DOI 10.1038/s41467-021-22350-6

  View details for PubMedID 33824343

• Topological insulators in the NaCaBi family with large spin-orbit coupling gaps PHYSICAL REVIEW RESEARCH Shao, D., Guo, Z., Wu, X., Nie, S., Sun, J., Weng, H., Wang, Z. 2021; 3 (1)

  View details for DOI 10.1103/PhysRevResearch.3.013278

  View details for Web of Science ID 000634569200001

• Quantum spin Hall effect in Ta2M3Te5 (M = Pd, Ni) PHYSICAL REVIEW B Guo, Z., Yan, D., Sheng, H., Nie, S., Shi, Y., Wang, Z. 2021; 103 (11)

  View details for DOI 10.1103/PhysRevB.103.115145

  View details for Web of Science ID 000646317500001

• Sixfold excitations in electrides PHYSICAL REVIEW RESEARCH Nie, S., Bernevig, B., Wang, Z. 2021; 3 (1)

  View details for DOI 10.1103/PhysRevResearch.3.L012028

  View details for Web of Science ID 000631260100004

• Unconventional Transverse Transport above and below the Magnetic Transition Temperature in Weyl Semimetal EuCd2As2 PHYSICAL REVIEW LETTERS Xu, Y., Das, L., Ma, J. Z., Yi, C. J., Nie, S. M., Shi, Y. G., Tiwari, A., Tsirkin, S. S., Neupert, T., Medarde, M., Shi, M., Chang, J., Shang, T. 2021; 126 (7): 076602

  Abstract

  As exemplified by the growing interest in the quantum anomalous Hall effect, the research on topology as an organizing principle of quantum matter is greatly enriched from the interplay with magnetism. In this vein, we present a combined electrical and thermoelectrical transport study on the magnetic Weyl semimetal EuCd_{2}As_{2}. Unconventional contribution to the anomalous Hall and anomalous Nernst effects were observed both above and below the magnetic transition temperature of EuCd_{2}As_{2}, indicating the existence of significant Berry curvature. EuCd_{2}As_{2} represents a rare case in which this unconventional transverse transport emerges both above and below the magnetic transition temperature in the same material. The transport properties evolve with temperature and field in the antiferromagnetic phase in a different manner than in the paramagnetic phase, suggesting different mechanisms to their origin. Our results indicate EuCd_{2}As_{2} is a fertile playground for investigating the interplay between magnetism and topology, and potentially a plethora of topologically nontrivial phases rooted in this interplay.

  View details for DOI 10.1103/PhysRevLett.126.076602

  View details for Web of Science ID 000619237200009

  View details for PubMedID 33666464

• Observation and control of the weak topological insulator state in ZrTe5. Nature communications Zhang, P., Noguchi, R., Kuroda, K., Lin, C., Kawaguchi, K., Yaji, K., Harasawa, A., Lippmaa, M., Nie, S., Weng, H., Kandyba, V., Giampietri, A., Barinov, A., Li, Q., Gu, G. D., Shin, S., Kondo, T. 2021; 12 (1): 406

  Abstract

  A quantum spin Hall (QSH) insulator hosts topological states at the one-dimensional (1D) edge, along which backscattering by nonmagnetic impurities is strictly prohibited. Its 3D analogue, a weak topological insulator (WTI), possesses similar quasi-1D topological states confined at side surfaces. The enhanced confinement could provide a route for dissipationless current and better advantages for applications relative to strong topological insulators (STIs). However, the topological side surface is usually not cleavable and is thus hard to observe. Here, we visualize the topological states of the WTI candidate ZrTe5 by spin and angle-resolved photoemission spectroscopy (ARPES): a quasi-1D band with spin-momentum locking was revealed on the side surface. We further demonstrate that the bulk band gap is controlled by external strain, realizing a more stable WTI state or an ideal Dirac semimetal (DS) state. The highly directional spin-current and the tunable band gap in ZrTe5 will provide an excellent platform for applications.

  View details for DOI 10.1038/s41467-020-20564-8

  View details for PubMedID 33462222

• 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

• Mapping Dirac fermions in the intrinsic antiferromagnetic topological insulators (MnBi2Te4)(Bi2Te3)(n) (n=0, 1) PHYSICAL REVIEW B Liang, Z., Luo, A., Shi, M., Zhang, Q., Nie, S., Ying, J. J., He, J., Wu, T., Wang, Z., Xu, G., Wang, Z., Chen, X. 2020; 102 (16)

  View details for DOI 10.1103/PhysRevB.102.161115

  View details for Web of Science ID 000579337200003

• Magnetic topological insulator MnBi6Te10 with a zero-field ferromagnetic state and gapped Dirac surface states PHYSICAL REVIEW B Tian, S., Gao, S., Nie, S., Qian, Y., Gong, C., Fu, Y., Li, H., Fan, W., Zhang, P., Kondo, T., Shin, S., Adell, J., Fedderwitz, H., Ding, H., Wang, Z., Qian, T., Lei, H. 2020; 102 (3)

  View details for DOI 10.1103/PhysRevB.102.035144

  View details for Web of Science ID 000550992900003

• Weyl semimetals with S-4 symmetry PHYSICAL REVIEW B Qian, Y., Gao, J., Song, Z., Nie, S., Wang, Z., Weng, H., Fang, Z. 2020; 101 (15)

  View details for DOI 10.1103/PhysRevB.101.155143

  View details for Web of Science ID 000529070900005

• Emergence of Nontrivial Low-Energy Dirac Fermions in Antiferromagnetic EuCd2 As2. Advanced materials (Deerfield Beach, Fla.) Ma, J. n., Wang, H. n., Nie, S. n., Yi, C. n., Xu, Y. n., Li, H. n., Jandke, J. n., Wulfhekel, W. n., Huang, Y. n., West, D. n., Richard, P. n., Chikina, A. n., Strocov, V. N., Mesot, J. n., Weng, H. n., Zhang, S. n., Shi, Y. n., Qian, T. n., Shi, M. n., Ding, H. n. 2020: e1907565

  Abstract

  Parity-time symmetry plays an essential role for the formation of Dirac states in Dirac semimetals. So far, all of the experimentally identified topologically nontrivial Dirac semimetals (DSMs) possess both parity and time reversal symmetry. The realization of magnetic topological DSMs remains a major issue in topological material research. Here, combining angle-resolved photoemission spectroscopy with density functional theory calculations, it is ascertained that band inversion induces a topologically nontrivial ground state in EuCd2 As2 . As a result, ideal magnetic Dirac fermions with simplest double cone structure near the Fermi level emerge in the antiferromagnetic (AFM) phase. The magnetic order breaks time reversal symmetry, but preserves inversion symmetry. The double degeneracy of the Dirac bands is protected by a combination of inversion, time-reversal, and an additional translation operation. Moreover, the calculations show that a deviation of the magnetic moments from the c-axis leads to the breaking of C3 rotation symmetry, and thus, a small bandgap opens at the Dirac point in the bulk. In this case, the system hosts a novel state containing three different types of topological insulator: axion insulator, AFM topological crystalline insulator (TCI), and higher order topological insulator. The results provide an enlarged platform for the quest of topological Dirac fermions in a magnetic system.

  View details for DOI 10.1002/adma.201907565

  View details for PubMedID 32091144

• Magnetic Semimetals and Quantized Anomalous Hall Effect in EuB_{6}. Physical review letters Nie, S. n., Sun, Y. n., Prinz, F. B., Wang, Z. n., Weng, H. n., Fang, Z. n., Dai, X. n. 2020; 124 (7): 076403

  Abstract

  Exploration of the novel relationship between magnetic order and topological semimetals has received enormous interest in a wide range of both fundamental and applied research. Here we predict that "soft" ferromagnetic material EuB_{6} can achieve multiple topological semimetal phases by simply tuning the direction of the magnetic moment. Explicitly, EuB_{6} is a topological nodal-line semimetal when the moment is aligned along the [001] direction, and it evolves into a Weyl semimetal with three pairs of Weyl points by rotating the moment to the [111] direction. Interestingly, we identify a composite semimetal phase featuring the coexistence of a nodal line and Weyl points with the moment in the [110] direction. Topological surface states and anomalous Hall conductivity, which are sensitive to the magnetic order, have been computed and are expected to be experimentally observable. Large-Chern-number quantum anomalous Hall effect can be realized in its [111]-oriented quantum-well structures.

  View details for DOI 10.1103/PhysRevLett.124.076403

  View details for PubMedID 32142316

• Topological electronic states in HfRuP family superconductors NPJ COMPUTATIONAL MATERIALS Qian, Y., Nie, S., Yi, C., Kong, L., Fang, C., Qian, T., Ding, H., Shi, Y., Wang, Z., Weng, H., Fang, Z. 2019; 5

  View details for DOI 10.1038/s41524-019-0260-6

  View details for Web of Science ID 000502990500002

• Topological crystalline insulators with C-2 rotation anomaly PHYSICAL REVIEW RESEARCH Zhang, T., Yue, C., Zhang, T., Nie, S., Wang, Z., Fang, C., Weng, H., Fang, Z. 2019; 1 (1)

  View details for DOI 10.1103/PhysRevResearch.1.012001

  View details for Web of Science ID 000600559800003

• Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd2As2 SCIENCE ADVANCES Ma, J., Nie, S. M., Yi, C. J., Jandke, J., Shang, T., Yao, M. Y., Naamneh, M., Yan, L. Q., Sun, Y., Chikina, A., Strocov, V. N., Medarde, M., Song, M., Xiong, Y., Xu, G., Wulfhekel, W., Mesot, J., Reticcioli, M., Franchini, C., Mudry, C., Mueller, M., Shi, Y. G., Qian, T., Ding, H., Shi, M. 2019; 5 (7): eaaw4718

  Abstract

  Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi-long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.

  View details for DOI 10.1126/sciadv.aaw4718

  View details for Web of Science ID 000478770400078

  View details for PubMedID 31309151

  View details for PubMedCentralID PMC6625818

• Topological nodal-line semimetals in ferromagnetic rare-earth-metal monohalides PHYSICAL REVIEW B Nie, S., Weng, H., Prinz, F. B. 2019; 99 (3)

  View details for DOI 10.1103/PhysRevB.99.035125

  View details for Web of Science ID 000455823600002

• Dirac semimetal in type-IV magnetic space groups PHYSICAL REVIEW B Hua, G., Nie, S., Song, Z., Yu, R., Xu, G., Yao, K. 2018; 98 (20)

  View details for DOI 10.1103/PhysRevB.98.201116

  View details for Web of Science ID 000452002100001

• Topological phases in the TaSe3 compound PHYSICAL REVIEW B Nie, S., Xing, L., Jin, R., Xie, W., Wang, Z., Prinz, F. B. 2018; 98 (12)

  View details for DOI 10.1103/PhysRevB.98.125143

  View details for Web of Science ID 000445726500004

• Orthorhombic carbon oC24: A novel topological nodal line semimetal CARBON Li, Z., Chen, J., Nie, S., Xu, L., Mizuseki, H., Weng, H., Wang, J. 2018; 133: 39-43

  View details for DOI 10.1016/j.carbon.2018.03.003

  View details for Web of Science ID 000431010600007

• Topological Nodal-Net Semimetal in a Graphene Network Structure PHYSICAL REVIEW LETTERS Wang, J., Nie, S., Weng, H., Kawazoe, Y., Chen, C. 2018; 120 (2): 026402

  Abstract

  Topological semimetals are characterized by the nodal points in their electronic structure near the Fermi level, either discrete or forming a continuous line or ring, which are responsible for exotic properties related to the topology of bulk bands. Here we identify by ab initio calculations a distinct topological semimetal that exhibits nodal nets comprising multiple interconnected nodal lines in bulk and have two coupled drumheadlike flat bands around the Fermi level on its surface. This nodal net semimetal state is proposed to be realized in a graphene network structure that can be constructed by inserting a benzene ring into each C─C bond in the bct-C_{4} lattice or by a crystalline modification of the (5,5) carbon nanotube. These results expand the realm of nodal manifolds in topological semimetals, offering a new platform for exploring novel physics in these fascinating materials.

  View details for DOI 10.1103/PhysRevLett.120.026402

  View details for Web of Science ID 000423131200017

  View details for PubMedID 29376700

• Topological semimetal in honeycomb lattice LnSI PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Nie, S., Xu, G., Prinz, F. B., Zhang, S. 2017; 114: 10596

  Abstract

  Recognized as elementary particles in the standard model, Weyl fermions in condensed matter have received growing attention. However, most of the previously reported Weyl semimetals exhibit rather complicated electronic structures that, in turn, may have raised questions regarding the underlying physics. Here, we report promising topological phases that can be realized in specific honeycomb lattices, including ideal Weyl semimetal structures, 3D strong topological insulators, and nodal-line semimetal configurations. In particular, we highlight a semimetal featuring both Weyl nodes and nodal lines. Guided by this model, we showed that GdSI, the long-perceived ideal Weyl semimetal, has two pairs of Weyl nodes residing at the Fermi level and that LuSI (YSI) is a 3D strong topological insulator with the right-handed helical surface states. Our work provides a mechanism to study topological semimetals and proposes a platform for exploring the physics of Weyl semimetals as well as related device designs.

  View details for DOI 10.1073/pnas.1713261114

  View details for PubMedCentralID PMC5635928

• Topological semimetal in honeycomb lattice LnSI. Proceedings of the National Academy of Sciences of the United States of America Nie, S., Xu, G., Prinz, F. B., Zhang, S. C. 2017; 114 (40): 10596-10600

  Abstract

  Recognized as elementary particles in the standard model, Weyl fermions in condensed matter have received growing attention. However, most of the previously reported Weyl semimetals exhibit rather complicated electronic structures that, in turn, may have raised questions regarding the underlying physics. Here, we report promising topological phases that can be realized in specific honeycomb lattices, including ideal Weyl semimetal structures, 3D strong topological insulators, and nodal-line semimetal configurations. In particular, we highlight a semimetal featuring both Weyl nodes and nodal lines. Guided by this model, we showed that GdSI, the long-perceived ideal Weyl semimetal, has two pairs of Weyl nodes residing at the Fermi level and that LuSI (YSI) is a 3D strong topological insulator with the right-handed helical surface states. Our work provides a mechanism to study topological semimetals and proposes a platform for exploring the physics of Weyl semimetals as well as related device designs.

  View details for DOI 10.1073/pnas.1713261114

  View details for PubMedID 28928149

  View details for PubMedCentralID PMC5635928

• Electronic structure of SrSn2As2 near the topological critical point SCIENTIFIC REPORTS Rong, L., Ma, J., Nie, S., Lin, Z., Li, Z., Fu, B., Kong, L., Zhang, X., Huang, Y., Weng, H., Qian, T., Ding, H., Tai, R. 2017; 7: 6133

  Abstract

  Topological materials with exotic quantum properties are promising candidates for quantum spin electronics. Different classes of topological materials, including Weyl semimetal, topological superconductor, topological insulator and Axion insulator, etc., can be connected to each other via quantum phase transition. For example, it is believed that a trivial band insulator can be twisted into topological phase by increasing spin-orbital coupling or changing the parameters of crystal lattice. With the results of LDA calculation and measurement by angle-resolved photoemission spectroscopy (ARPES), we demonstrate in this work that the electronic structure of SrSn2As2 single crystal has the texture of band inversion near the critical point. The results indicate the possibility of realizing topological quantum phase transition in SrSn2As2 single crystal and obtaining different exotic quantum states.

  View details for DOI 10.1038/s41598-017-05386-x

  View details for Web of Science ID 000406285700041

  View details for PubMedID 28733663

  View details for PubMedCentralID PMC5522476

• Electronic evidence of temperature-induced Lifshitz transition and topological nature in ZrTe5 NATURE COMMUNICATIONS Zhang, Y., Wang, C., Yu, L., Liu, G., Liang, A., Huang, J., Nie, S., Sun, X., Zhang, Y., Shen, B., Liu, J., Weng, H., Zhao, L., Chen, G., Jia, X., Hu, C., Ding, Y., Zhao, W., Gao, Q., Li, C., He, S., Zhao, L., Zhang, F., Zhang, S., Yang, F., Wang, Z., Peng, Q., Dai, X., Fang, Z., Xu, Z., Chen, C., Zhou, X. J. 2017; 8: 15512

  Abstract

  The topological materials have attracted much attention for their unique electronic structure and peculiar physical properties. ZrTe5 has host a long-standing puzzle on its anomalous transport properties manifested by its unusual resistivity peak and the reversal of the charge carrier type. It is also predicted that single-layer ZrTe5 is a two-dimensional topological insulator and there is possibly a topological phase transition in bulk ZrTe5. Here we report high-resolution laser-based angle-resolved photoemission measurements on the electronic structure and its detailed temperature evolution of ZrTe5. Our results provide direct electronic evidence on the temperature-induced Lifshitz transition, which gives a natural understanding on underlying origin of the resistivity anomaly in ZrTe5. In addition, we observe one-dimensional-like electronic features from the edges of the cracked ZrTe5 samples. Our observations indicate that ZrTe5 is a weak topological insulator and it exhibits a tendency to become a strong topological insulator when the layer distance is reduced.

  View details for DOI 10.1038/ncomms15512

  View details for Web of Science ID 000401849600001

  View details for PubMedID 28534501

  View details for PubMedCentralID PMC5457516

• Experimental evidence of hourglass fermion in the candidate nonsymmorphic topological insulator KHgSb SCIENCE ADVANCES Ma, J., Yi, C., Lv, B., Wang, Z., Nie, S., Wang, L., Kong, L., Huang, Y., Richard, P., Zhang, P., Yaji, K., Kuroda, K., Shin, S., Weng, H., Bernevig, B., Shi, Y., Qian, T., Ding, H. 2017; 3 (5): e1602415

  Abstract

  Topological insulators (TIs) host novel states of quantum matter characterized by nontrivial conducting boundary states connecting valence and conduction bulk bands. All TIs discovered experimentally so far rely on either time-reversal or mirror crystal symmorphic symmetry to protect massless Dirac-like boundary states. Several materials were recently proposed to be TIs with nonsymmorphic symmetry, where a glide mirror protects exotic surface fermions with hourglass-shaped dispersion. However, an experimental confirmation of this new fermion is missing. Using angle-resolved photoemission spectroscopy, we provide experimental evidence of hourglass fermions on the (010) surface of crystalline KHgSb, whereas the (001) surface has no boundary state, in agreement with first-principles calculations. Our study will stimulate further research activities of topological properties of nonsymmorphic materials.

  View details for DOI 10.1126/sciadv.1602415

  View details for Web of Science ID 000401955300019

  View details for PubMedID 28508059

  View details for PubMedCentralID PMC5419706

• Superconductivity in HfTe5 across weak to strong topological insulator transition induced via pressures SCIENTIFIC REPORTS Liu, Y., Long, Y. J., Zhao, L. X., Nie, S. M., Zhang, S. J., Weng, Y. X., Jin, M. L., Li, W. M., Liu, Q. Q., Long, Y. W., Yu, R. C., Gu, C. Z., Sun, F., Yang, W. G., Mao, H. K., Feng, X. L., Li, Q., Zheng, W. T., Weng, H. M., Dai, X., Fang, Z., Chen, G. F., Jin, C. Q. 2017; 7: 44367

  Abstract

  Recently, theoretical studies show that layered HfTe5 is at the boundary of weak &strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice parameters. The topological properties of 3D stacked HfTe5 are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic &crystal structures for HfTe5 with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe5 crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe5 transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe5 is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.

  View details for DOI 10.1038/srep44367

  View details for Web of Science ID 000396572000001

  View details for PubMedID 28300156

  View details for PubMedCentralID PMC5353664

• Observation of Fermi arc and its connection with bulk states in the candidate type-II Weyl semimetal WTe2 PHYSICAL REVIEW B Wang, C., Zhang, Y., Huang, J., Nie, S., Liu, G., Liang, A., Zhang, Y., Shen, B., Liu, J., Hu, C., Ding, Y., Liu, D., Hu, Y., He, S., Zhao, L., Yu, L., Hu, J., Wei, J., Mao, Z., Shi, Y., Jia, X., Zhang, F., Zhang, S., Yang, F., Wang, Z., Peng, Q., Weng, H., Dai, X., Fang, Z., Xu, Z., Chen, C., Zhou, X. J. 2016; 94 (24)

  View details for DOI 10.1103/PhysRevB.94.241119

  View details for Web of Science ID 000391014200001

• Angle-resolved photoemission observation of Mn-pnictide hybridization and negligible band structure renormalization in BaMn2As2 and BaMn2Sb2 PHYSICAL REVIEW B Zhang, W., Richard, P., van Roekeghem, A., Nie, S., Xu, N., Zhang, P., Miao, H., Wu, S., Yin, J., Fu, B. B., Kong, L., Qian, T., Wang, Z., Fang, Z., Sefat, A. S., Biermann, S., Ding, H. 2016; 94 (15)

  View details for DOI 10.1103/PhysRevB.94.155155

  View details for Web of Science ID 000386615900002

• Spontaneous Formation of a Superconductor-Topological Insulator-Normal Metal Layered Heterostructure ADVANCED MATERIALS Wang, Y., Wu, X., Wang, Y., Shao, Y., Lei, T., Wang, J., Zhu, S., Guo, H., Zhao, L., Chen, G., Nie, S., Weng, H., Ibrahim, K., Dai, X., Fang, Z., Gao, H. 2016; 28 (25): 5013-5017

  Abstract

  2D materials with heterolayered structures beyond graphene are explored. A theoretically predicted superconductor-topological insulator-normal metal heterolayered structure is realized experimentally. The generated hybrid structure HfTe3 /HfTe5 /Hf has potential applications in both quantum-spin Hall effect-based and Majorana-based devices.

  View details for DOI 10.1002/adma.201600575

  View details for Web of Science ID 000378940100007

  View details for PubMedID 27087261

• Body-Centered Orthorhombic C-16: A Novel Topological Node-Line Semimetal PHYSICAL REVIEW LETTERS Wang, J., Weng, H., Nie, S., Fang, Z., Kawazoe, Y., Chen, C. 2016; 116 (19): 195501

  Abstract

  We identify by ab initio calculations a novel topological semimetal carbon phase in all-sp^{2} bonding networks with a 16-atom body-centered orthorhombic unit cell, termed bco-C_{16}. Total-energy calculations show that bco-C_{16} is comparable to solid fcc-C_{60} in energetic stability, and phonon and molecular dynamics simulations confirm its dynamical stability. This all-sp^{2} carbon allotrope can be regarded as a three-dimensional modification of graphite, and its simulated x-ray diffraction (XRD) pattern matches well a previously unexplained diffraction peak in measured XRD spectra of detonation and chimney soot, indicating its presence in the specimen. Electronic band structure calculations reveal that bco-C_{16} is a topological node-line semimetal with a single nodal ring. These findings establish a novel carbon phase with intriguing structural and electronic properties of fundamental significance and practical interest.

  View details for DOI 10.1103/PhysRevLett.116.195501

  View details for Web of Science ID 000376011700007

  View details for PubMedID 27232027

• Evidence for Topological Edge States in a Large Energy Gap near the Step Edges on the Surface of ZrTe5 PHYSICAL REVIEW X Wu, R., Ma, J., Nie, S., Zhao, L., Huang, X., Yin, J., Fu, B., Richard, P., Chen, G., Fang, Z., Dai, X., Weng, H., Qian, T., Ding, H., Pan, S. H. 2016; 6 (2)

  View details for DOI 10.1103/PhysRevX.6.021017

  View details for Web of Science ID 000376010400001

• Band gap anomaly and topological properties in lead chalcogenides CHINESE PHYSICS B Nie, S., Xu, X., Xu, G., Fang, Z. 2016; 25 (3)

  View details for DOI 10.1088/1674-1056/25/3/037311

  View details for Web of Science ID 000375647400057

• Two-dimensional oxide topological insulator with iron-pnictide superconductor LiFeAs structure PHYSICAL REVIEW B Xu, Q., Song, Z., Nie, S., Weng, H., Fang, Z., Dai, X. 2015; 92 (20)

  View details for DOI 10.1103/PhysRevB.92.205310

  View details for Web of Science ID 000365508300006

• Observation of Fermi-Arc Spin Texture in TaAs PHYSICAL REVIEW LETTERS Lv, B. Q., Muff, S., Qian, T., Song, Z. D., Nie, S. M., Xu, N., Richard, P., Matt, C. E., Plumb, N. C., Zhao, L. X., Chen, G. F., Fang, Z., Dai, X., Dil, J. H., Mesot, J., Shi, M., Weng, H. M., Ding, H. 2015; 115 (21): 217601

  Abstract

  We have investigated the spin texture of surface Fermi arcs in the recently discovered Weyl semimetal TaAs using spin- and angle-resolved photoemission spectroscopy. The experimental results demonstrate that the Fermi arcs are spin polarized. The measured spin texture fulfills the requirement of mirror and time-reversal symmetries and is well reproduced by our first-principles calculations, which gives strong evidence for the topologically nontrivial Weyl semimetal state in TaAs. The consistency between the experimental and calculated results further confirms the distribution of chirality of the Weyl nodes determined by first-principles calculations.

  View details for DOI 10.1103/PhysRevLett.115.217601

  View details for Web of Science ID 000364910000010

  View details for PubMedID 26636872

• Quantum spin Hall effect in two-dimensional transition-metal dichalcogenide haeckelites PHYSICAL REVIEW B Nie, S. M., Song, Z., Weng, H., Fang, Z. 2015; 91 (23)

  View details for DOI 10.1103/PhysRevB.91.235434

  View details for Web of Science ID 000356480400003

• Direct spectroscopic evidence for completely filled Cu 3d shell in BaCu2As2 and alpha-BaCu2Sb2 PHYSICAL REVIEW B Wu, S. F., Richard, P., van Roekeghem, A., Nie, S. M., Miao, H., Xu, N., Qian, T., Saparov, B., Fang, Z., Biermann, S., Sefat, A. S., Ding, H. 2015; 91 (23)

  View details for DOI 10.1103/PhysRevB.91.235109

  View details for Web of Science ID 000355720600001

• Raman scattering investigation of the electron-phonon coupling in superconducting Nd(O,F)BiS2 PHYSICAL REVIEW B Wu, S. F., Richard, P., Wang, X. B., Lian, C. S., Nie, S. M., Wang, J. T., Wang, N. L., Ding, H. 2014; 90 (5)

  View details for DOI 10.1103/PhysRevB.90.054519

  View details for Web of Science ID 000341299200005

• Observation of anomalous temperature dependence of spectrum on small Fermi surfaces in a BiS2-based superconductor PHYSICAL REVIEW B Zeng, L. K., Wang, X. B., Ma, J., Richard, P., Nie, S. M., Weng, H. M., Wang, N. L., Wang, Z., Qian, T., Ding, H. 2014; 90 (5)

  View details for DOI 10.1103/PhysRevB.90.054512

  View details for Web of Science ID 000344011300003

• Optical spectroscopy study of Nd(O,F)BiS2 single crystals PHYSICAL REVIEW B Wang, X. B., Nie, S. M., Wang, H. P., Zheng, P., Wang, P., Dong, T., Weng, H. M., Wang, N. L. 2014; 90 (5)

  View details for DOI 10.1103/PhysRevB.90.054507

  View details for Web of Science ID 000341161400007