Quant-ph 20180611 Disorder enabled band structure engineering of a topological insulator surface

Title: Disorder enabled band structure engineering of a topological insulator surface
Speaker: Dr. Yishuai Xu from New York University
Time: 14:00 pm June 11 (Monday), 2018
Place: TDLI Meeting Room 410, 4th floor of TD Lee Library
Host: Prof. Weidong Luo


Three-dimensional Topological Insulators are bulk insulators with Z2 topological order that give rise to Dirac surface states. These states are well protected against weak perturbations that does not break time-reversal symmetry such as non-magnetic potential disorders. However recent studies have shown that non-magnetic point-like defects can introduce new in-gap states. We developed a numerical model to simulate point defects on a TI surface. We find that resonance state associated with the defects can hybridizes with the Dirac cone surface state and create kink-like feature in the band structure near the Dirac point. These resonance state are not Anderson localized even though they cluster around the defects sites. We discovered that these resonance states support diffusive transport in simulation and can be used to engineer the band structure of a TI since defect densities and chemical potential are controllable during sample growth. We also performed Dichroic and micro ARPES measurements to confirm the existence of these resonance states.




Yishuai is currently a Ph.D. student in New York University. He works as a research assistant in Prof. Andrew Wray’s lab. Yishuai got his bachelor’s degree in Physics from Shanghai Jiao Tong University in 2014 where he conducted research in Prof. Weidong Luo’s lab.



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