Xiaoxiang Xi is a professor at School of Physics, Nanjing University. He received his bachelor's degree at Nanjing University in 2007 and PhD at University of Florida, USA in 2011. Prior to joining the faculty at Nanjing University in 2016, he was a postdoctoral research associate at Brookhaven National Laboratory (2012-2014) and Pennsylvania State University (2014-2016).

Curriculum vitae (CV)

In solid-state materials, the interplay of lattice, electronic, and spin degrees of freedom can often lead to novel ground states, intellectually interesting and potentially useful for applications. At reduced dimensions, even more exotic states can be uncovered, thanks to the concerted action of quantum mechanics and stronger Coulomb interaction. In the past two decades, a powerful set of tools have been developed, enabling investigation and control of materials confined in the two and one-dimensional space.

My group explore the optical and electronic properties of low-dimensional quantum materials, with a focus on collective phenomena related to the multiple degrees of freedom in crystals. Some specific examples include:

■ Charge-density waves

■ Two-dimensional superconductivity

■ Topological materials

■ Ferroic materials

Selected publications：

1. Y. Du†, G. Liu†, W. Ruan†, Z. Fang, K. Watanabe, T. Taniguchi, R. Liu, J.-X. Li, X. Xi*, “Unveiling resilient superconducting fluctuations in atomically thin NbSe₂ through Higgs mode spectroscopy”, Physical Review Letters 134, 066002 (2025). (Editors' Suggestion)

     Featured in Physics: Strong Hints of a Bose Metal

2. Y. Li†*, L. Xu†, G. Liu†, Y. Fang†, H. Zheng, S. Dai, E. Li, G. Zhu, S. Zhang, S. Liang, L. Yang, F. Huang, X. Xi*, Z. Liu*, N. Xu*, and Y. Chen, “Evidence of strong and mode-selective electron-phonon coupling in the topological superconductor candidate 2M-WS₂”, Nature Communications 15, 6235 (2024).

3. G. Liu†, T. Qiu†, K. He†, Y. Liu, D. Lin, Z. Ma, Z. Huang, W. Tang, J. Xu, K. Watanabe, T. Taniguchi, L. Gao, J. Wen, J.-M. Liu, B. Yan*, and X. Xi*, “Electrical switching of ferro-rotational order in nanometre-thick 1T-TaS₂ crystals”, Nature Nanotechnology 18, 854 (2023).

     News & Views: Voltage enables ferro-rotational domain switching

4.  H. F. Yang†, K. Y. He†, J. Koo†, S. W. Shen, S. H. Zhang, G. Liu, Y. Z. Liu, C. Chen, A. J. Liang, K. Huang, M. X. Wang, J. J. Gao, X. Luo, L. X. Yang, J. P. Liu, Y. P. Sun, S. C. Yan, B. H. Yan*, Y. L. Chen*, X. Xi*, and Z. K. Liu*, “Visualization of chiral electronic structure and anomalous optical response in a material with chiral charge density waves”, Physical Review Letters 129, 156401 (2022). 

5.  G. Liu, X. Ma, K. He, Q. Li, H. Tan, Y. Liu, J. Xu, W. Tang, K. Watanabe, T. Taniguchi, L. Gao, Y. Dai, H.-H. Wen, B. Yan* & X. Xi*, “Observation of anomalous amplitude modes in the kagome metal CsV₃Sb₅”, Nature Communications 13, 3461 (2022). 

6. D. Lin, S. Li, J. Wen, H. Berger, L. Forró, H. Zhou, S. Jia, T. Taniguchi, K. Watanabe, X. Xi*, and M. S. Bahramy*, “Patterns and driving forces of dimensionality-dependent charge density waves in 2H-type transition metal dichalcogenides”, Nature Communications 11, 2406 (2020). 

7. X. Xi†, Z. Wang†, K. T. Law, H. Berger, L. Forró, J. Shan*, and K. F. Mak*, “Ising paring in superconducting NbSe₂ atomic layers”, Nature Physics 12, 139 (2016).  

     News & Views: The Ising on the monolayer

8. X. Xi, H. Berger, L. Forró, J. Shan*, and K. F. Mak*, “Gate tuning of electronic phase transitions in two-dimensional NbSe₂”, Physical Review Letters 117, 106801 (2016). (Editors' Suggestion)

9. X. Xi, L. Zhao, Z. Wang, H. Berger, L. Forró, J. Shan*, and K. F. Mak*, “Strongly enhanced charge density wave order in monolayer NbSe2”, Nature Nanotechnology 10, 765 (2015).

     News & Views: Charge density waves go nano

10. X. Xi, X.-G. He, F. Guan, Z. Liu, R. D. Zhong, J. A. Schneeloch, T. S. Liu, G. D. Gu, X. Du, Z. Chen, X. G. Hong, W. Ku, and G. L. Carr, “Bulk signatures of pressure-induced band inversion and topological phase transitions in Pb_1−xSn_xSe”, Physical Review Letters 113, 096401 (2014).

11. X. Xi, C. Ma, Z. Liu, Z. Chen, W. Ku, H. Berger, C. Martin, D. B. Tanner, and G. L. Carr, “Signatures of a pressure-induced topological quantum phase transition in BiTeI”, Physical Review Letters 111, 155701 (2013).

12. X. Xi, J. Hwang, C. Martin, D. B. Tanner, and G. L. Carr, “Far-infrared conductivity measurements of pair breaking in superconducting Nb_0.5Ti_0.5N thin films induced by an external magnetic field”, Physical Review Letters 105, 257006 (2010).