CHENHANG XU

All Publications

• Comment on "Photoinduced Dynamics and Momentum Distribution of Chiral Charge Density Waves in 1T-TiSe₂" PHYSICAL REVIEW LETTERS Xu, C., McClellan, J., Liu, P., Lin, S., Pan, S., Bell, H. G., Kramer, P. L., Lemons, R., Philip, S. S., Duncan, C. J. R., Kaufman, B., Mo, M., Reid, A. H., Cerullo, G., Zong, A., Zuerch, M. W. 2026; 137 (2)

  View details for DOI 10.1103/p5d8-548h

  View details for Web of Science ID 001824444300004

• Comment on "Photoinduced Dynamics and Momentum Distribution of Chiral Charge Density Waves in 1T-TiSe_{2}". Physical review letters Xu, C., McClellan, J., Liu, P., Lin, S. C., Pan, S., Bell, H. G., Kramer, P. L., Lemons, R., Philip, S. S., Duncan, C. J., Kaufman, B., Mo, M., Reid, A. H., Cerullo, G., Zong, A., Zuerch, M. W. 2026; 137 (2): 029601

  View details for DOI 10.1103/p5d8-548h

  View details for PubMedID 42503136

• Structural Contribution to Light-Induced Gap Suppression in Ta_{2}NiSe_{5}. Physical review letters Chen, Z., Xu, C., Xie, C., Tang, W., Liu, Q., Wu, D., Xu, Q., Jiang, T., Zhu, P., Zou, X., Li, J., Wang, Z., Wang, N., Qian, D., Zong, A., Xiang, D. 2025; 135 (9): 096901

  Abstract

  An excitonic insulator is a material that hosts an exotic ground state, where an energy gap opens due to spontaneous condensation of bound electron-hole pairs. Ta_{2}NiSe_{5} is a promising candidate for this type of material, but the coexistence of a structural phase transition with the gap opening has led to a long-standing debate regarding the origin of the insulating gap. Here we employ MeV ultrafast electron diffraction to obtain quantitative insights into the atomic displacements in Ta_{2}NiSe_{5} following photoexcitation, which has been overlooked in previous time-resolved spectroscopy studies. In conjunction with first-principles calculations using the measured atomic displacements, we find that the structural change can largely account for the photoinduced reduction in the energy gap without considering excitonic effects. Our Letter illustrates the importance of a quantitative reconstruction of individual atomic pathways during nonequilibrium phase transitions, paving the way for a mechanistic understanding of a diverse array of phase transitions in correlated materials where lattice dynamics can play a pivotal role.

  View details for DOI 10.1103/1kzk-sz7g

  View details for PubMedID 40952197

• Structural Contribution to Light-Induced Gap Suppression in Ta2NiSe5 PHYSICAL REVIEW LETTERS Chen, Z., Xu, C., Xie, C., Tang, W., Liu, Q., Wu, D., Xu, Q., Jiang, T., Zhu, P., Zou, X., Li, J., Wang, Z., Wang, N., Qian, D., Zong, A., Xiang, D. 2025; 135 (9)

  View details for DOI 10.1103/1kzk-sz7g

  View details for Web of Science ID 001563968300001

• Giant electrocaloric effect in high-polar-entropy perovskite oxides NATURE Du, F., Yang, T., Hao, H., Li, S., Xu, C., Yao, T., Song, Z., Shen, J., Bai, C., Luo, R., Han, D., Li, Q., Zheng, S., Zhang, Y., Lin, Y., Ma, Z., Chen, H., Guo, C., Feng, J., Zhong, S., Mai, R., Hou, G., Qiu, H., Xie, M., Chen, X., Yuan, Y., Qian, D., Xiang, D., Chen, X., Fu, Z., Wang, G., Liu, H., Chen, J., Meng, G., Zhu, X., Chen, L., Zhang, S., Qian, X. 2025; 640 (8060): 924-930

  Abstract

  Materials with a high electrocaloric effect (ECE)1,2 tend to favour a disordered yet easily tunable polar structure. Perovskite ferroelectrics3 stand out as ideal candidates owing to their high dielectric responses and reasonable thermal conductivity. The introduction of multielement atomic distortions induces a high-polar-entropy state4 that notably increases the ECE by effectively overcoming the constraints imposed by highly ordered, polar-correlated perovskite structures. Here we developed a lead-free relaxor ferroelectric with strong polar disorder through targeted multielement substitution at both the A and B sites of the perovskite, effectively distorting the lattice structure and inducing a variety of nanoscale polar configurations, polymorphic polar variants and non-polar regions. A combination of these multielement-induced features led to an increased density of interfaces, significantly enhancing the polar entropy. Remarkably, a high ECE for an entropy change of about 15 J kg-1 K-1 under a 10 MV m-1 field is observed for the material across a broad temperature range exceeding 60 °C. The formation of ultrafine, dispersed, multiphase lattice configurations leads to high-polar-entropy ferroelectric oxides with a high ECE and a long lifetime of over 1 million cycles that are suitable for manufacturing multilayer ceramic capacitors for practical electrocaloric refrigeration applications.

  View details for DOI 10.1038/s41586-025-08768-8

  View details for Web of Science ID 001462520400001

  View details for PubMedID 40205056

  View details for PubMedCentralID 10957880

• Time-domain study of coupled collective excitations in quantum materials NPJ QUANTUM MATERIALS Xu, C., Zong, A. 2025; 10 (1)

  View details for DOI 10.1038/s41535-025-00726-x

  View details for Web of Science ID 001421278900002

• Transient dynamics of the phase transition in VO₂ revealed by mega-electron-volt ultrafast electron diffraction NATURE COMMUNICATIONS Xu, C., Jin, C., Chen, Z., Lu, Q., Cheng, Y., Zhang, B., Qi, F., Chen, J., Yin, X., Wang, G., Xiang, D., Qian, D. 2023; 14 (1): 1265

  Abstract

  Vanadium dioxide (VO2) exhibits an insulator-to-metal transition accompanied by a structural transition near room temperature. This transition can be triggered by an ultrafast laser pulse. Exotic transient states, such as a metallic state without structural transition, were also proposed. These unique characteristics let VO2 have great potential in thermal switchable devices and photonic applications. Although great efforts have been made, the atomic pathway during the photoinduced phase transition is still not clear. Here, we synthesize freestanding quasi-single-crystal VO2 films and examine their photoinduced structural phase transition with mega-electron-volt ultrafast electron diffraction. Leveraging the high signal-to-noise ratio and high temporal resolution, we observe that the disappearance of vanadium dimers and zigzag chains does not coincide with the transformation of crystal symmetry. After photoexcitation, the initial structure is strongly modified within 200 femtoseconds, resulting in a transient monoclinic structure without vanadium dimers and zigzag chains. Then, it continues to evolve to the final tetragonal structure in approximately 5 picoseconds. In addition, only one laser fluence threshold instead of two thresholds suggested in polycrystalline samples is observed in our quasi-single-crystal samples. Our findings provide essential information for a comprehensive understanding of the photoinduced ultrafast phase transition in VO2.

  View details for DOI 10.1038/s41467-023-37000-2

  View details for Web of Science ID 000957599200004

  View details for PubMedID 36882433

  View details for PubMedCentralID PMC9992676

• Manipulating the magneto-resistance of Bi₂Se₃ thin films by strontium doping JOURNAL OF APPLIED PHYSICS Hu, J., Jiang, W., Lu, Q., Xu, C., Wu, J., Jiao, J., Wang, G., Ma, J., Qian, D. 2022; 132 (9)

  View details for DOI 10.1063/5.0092075

  View details for Web of Science ID 000978622900004

• Coexistence of Ferroelectriclike Polarization and Dirac-like Surface State in TaNiTe₅ PHYSICAL REVIEW LETTERS Li, Y., Ran, Z., Huang, C., Wang, G., Shen, P., Huang, H., Xu, C., Liu, Y., Jiao, W., Jiang, W., Hu, J., Zhu, G., Xu, C., Lu, Q., Wang, G., Jing, Q., Wang, S., Shi, Z., Jia, J., Xu, X., Zhang, W., Luo, W., Qian, D. 2022; 128 (10): 106802

  Abstract

  By combining angle-resolved photoemission spectroscopy, scanning tunneling microscopy, atomic force microscope based piezoresponse force microscopy and first-principles calculations, we have studied the low-energy band structure, atomic structure, and charge polarization on the surface of a topological semimetal candidate TaNiTe_{5}. Dirac-like surface states were observed on the (010) surface by angle-resolved photoemission spectroscopy, consistent with the first-principles calculations. On the other hand, piezoresponse force microscopy reveals a switchable ferroelectriclike polarization on the same surface. We propose that the noncentrosymmetric surface relaxation observed by scanning tunneling microscopy could be the origin of the observed ferroelectriclike state in this novel material. Our findings provide a new platform with the coexistence of a ferroelectriclike surface charge distribution and novel surface states.

  View details for DOI 10.1103/PhysRevLett.128.106802

  View details for Web of Science ID 000767685400005

  View details for PubMedID 35333064

• Magnetic properties of the quasi two-dimensional centered honeycomb antiferromagnet GdInO₃ PHYSICAL REVIEW B Yin, X., Li, Y., Wang, G., Hu, J., Xu, C., Lu, Q., Zhong, Y., Zhao, J., Zhao, X., Zhang, Y., Cao, Y., Xu, K., Li, Z., Kamiya, Y., Hong, G., Qian, D. 2021; 104 (13)

  View details for DOI 10.1103/PhysRevB.104.134432

  View details for Web of Science ID 000747136300005