Detail:
Abstract: I will discuss two examples of magneto-optical transport properties in gapped Dirac materials, focusing on 2D transition-metal dichalcogenides (TMD) and topological insulators (TI). First we will talk about the use of Faraday effect to measure the intrinsic spin fluctuations and how this facilitates the extraction of spin relaxation time in 2D TMD. It is shown that spin noise measurement provides a non-invasive method to probe the spin and valley dynamics and relaxation of 2D TMD. Secondly, we will discuss the effects of coherent excitation on TI by a strong electromagnetic field under time-reversal symmetry breaking. A signature of optical Stark effect is found to be present in the resulting nonlinear Faraday and Kerr rotations caused by conduction-valence band mixing by the optical dipole matrix element. These two examples illustrate that magneto-optics provides a useful alternative to studying spin relaxation and coherent optical properties traditionally studied using pump-probe techniques.
Biosketch: Dr. Wang-Kong Tse obtained his BEng at University of Hong Kong in 1999, M.Phil. at Chinese University of Hong Kong in 2003, and Ph.D. in theoretical condensed matter physics at University of Maryland, College Park in 2008. After working at University of Texas at Austin as a postdoctoral research associate, he joined Los Alamos National Laboratory as a director’s postdoctoral fellow in 2013 and worked as an assistant professor at University of Alabama in 2015. His main research topics are light-matter interaction in low-dimensional systems, many-body effects in electronic and transport properties, and quantum spintronics and topological phases.
