Dr. Chang-An Li: Random flux induced topological quantum phase transitions (2025/06/23)

Title	Random flux induced topological quantum phase transitions
Speaker	Dr. Chang-An Li Würzburg University, Germany
Time	10：00am, June 23, 2025
Place	Material Science and Research Building B902
Brief Bio of the Speaker	Dr. Chang-An Li is a postdoc researcher at institute for theoretical physics and astrophysics, Würzburg University, Germany. He obtained his B.S. from Beijing Normal University in 2014 and his Ph.D in physics from The University of Hong Kong in 2019 under supervision of Prof. Shun-Qing Shen. After working as a postdoc at Westlake University in 2020, he moved to Würzburg University as a postdoc researcher. His research mainly focuses on topological phases of matter, disorder effect, and non-Hermitian physics. He has published 20+ first/corresponding author papers, including Physical Review Letters selected as Editors’ suggestion and On the cover.
Abstract	Random flux is an important type of disorder which has deep connections to many fundamental phenomena such as the fractional quantum Hall effect. However, its impact on topological states of matter has remained largely elusive. In this talk, I will first discuss how will disorder drive higher-order topological nontrivial phases, i.e., higher-order topological Anderson insulators[1]. Then I will present the random-flux-driven quantum phase transition from metals to higher-order topological insulators[2]. Finally, I will show the particular successive phase transition sequence between weak and strong topological phases induced by random flux and the consequent new quantum criticality that lies outside quantum Hall universality[3]. References: 1. C. A. Li et al., Physical Review Letter 125 166801(2020); 2. C. A. Li et al., Physical Review B 106, L081410 (2022); 3. C. A. Li et al., arXiv: 2411.09780, Physical Review B in press (2025).


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