Time：November 16 2021, 16:00-17:30

Venue: BAQIS Meeting Room 526

Tencent Meeting ID: 300 187 946

Title：Quantum Phase Transition in Quantum Anomalous Hall Insulators

Host：Kai Chang, Research Scientist, BAQIS

Abstract：When approaching the phase transition, the observable quantities display power-law behaviors due to the strong fluctuation of the order parameter. The exponents of these power-laws are known as critical exponents, and they are nominally universal. That is, the same values are often shared between disparate systems. However, this universality is found absent in the localization-delocalization transition of quantum Hall materials. In this talk, I will talk about the scaling behaviors of the localization-delocalization transition in the quantum anomalous Hall (QAH) insulators with different levels of disorder. By applying complementary approaches, we found that the absence of universality is due to the variability in the temperature exponent p, which relates temperature to the inelastic scattering length (Ls) and is disorder-dependent. Then, I will talk about the results for mesoscopic QAH samples with the size on the order of Ls. By examining their scaling behavior, we directly measured the Ls of QAH insulators.   

About the Speaker：Peng Deng received his bachelor’s degree in physics from the University of Science and Technology of China in 2009. Then he started his Ph.D. research in the department of physics, Tsinghua University. After receiving his Ph.D. degree, in 2016 he joined the Device Research Lab at the University of California, Los Angeles for postdoc research. His research includes MBE growth and transport/STM study of low-dimensional materials. Currently, his research interest focuses on magnetic topological insulators and quantum anomalous Hall insulators.