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Three-dimensional Quantum Hall Effect and Metal-insulator Transition in ZrTe5


Speaker:Prof. Liyuan Zhang
Affiliation:Department of Physics, Southern University of Science and Technology
Date:September 9, 2019 (Monday)
Time:2:30 p.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU

Abstract

The discovery of quantum Hall effect had greatly improved the understanding of the phase transitions and topological orders in two-dimentional systems. It is natural to ask whether there are similar phemomena that might occur in three-dimentional gas systems. However, the long-sought three-dimensional (3D) quantum Hall effect has not been well experimentally demonstrated in 3D gas system. Here we report an experimental observation of three-dimensional quantum Hall effect in zirconium Penta-telluride(ZrTe5)within a magnetic field B (<1.3T). We also discover that each Quantum Layer contributes 2e2/h with a thickness of one Fermi wavelength λF in b direction. As further increasing magnetic field, the system has reached the Quantum Limit regime, where the resistance ρxx(B) increases dramatically and displays Metal-Insulator transition behavior. With analysing ρxx(B) scaling plots, we confirm this Metal-Insulator transition is a many-body quantum topological phase transition. Our finding not only provides a new understanding of the interplay between 2D and 3D Landau quantization but also allow for the further exploration of the higher dimensional electronic gas system and exotic strongly corrected topological phase transitions.
References:
[1] FD. Tang †, YF. Ren †, P P. Wang, R.D. Zhong, J . Schneeloch, , S. A. Yang*, K. Yang, P . A. Lee, G. Gu, ZH. Qiao*, and LY. Zhang*,“Three-dimensional quantum Hall effect and metal-insulator transition in ZrTe5", Nature 569, 537 (2019).
[2] Wenjie Zhang, Peipei Wang, Brian Skinner, Ran Bi, Vladyslav Kozii, Chang-Woo Cho, Ruidan Zhong, John Schneeloch, Dapeng Yu, Genda Gu, Liang Fu, Xiaosong Wu, Liyuan Zhang,"Quantized plateau in the thermoelectric Hall conductivity for Dirac electrons in the extreme quantum limit”arxiv:1904.02157, (2019).

Biography

Dr. Liyuan Zhang is the associate professor at Southern University of Science and Technology (SUSTech). He received his Ph.D. degree (2007) from Georgia Institute of Technology. After doing postdoctoral study at Purdue University, Brookhaven National Laboratory, and Stony Brook University, etc, he then joined the faculty of department of physics in Renmin University of China. In 2014, he moved to current position in SUSTech. His research interests are mainly in transport exploring and understanding physical laws governing electrons, spins and phonons in various materials and artificial systems, with the aim to uncover novel quantum phenomena and new states of matter and to excavate new applications in quantum devices and nanotechnology (such as nanoelectronics and nanofabrication).

Coffee and tea will be served 20 minutes prior to the seminar.

Anyone interested is welcome to attend.