The compound SmB6 has been of broad interest over the last few years as the prototypical example of a topological Kondo insulator (TKI), in which topological surface states emerge at low temperature through the coherence of strongly correlated electrons. However, the material remains enigmatic in many ways. Understanding of the low energy electronic band structure is fragmentary, complicated by a polar surface termination and poor experimental resolution of the bulk bands. I will talk about how powerful new measurement and analysis techniques at spectromicroscopy beamlines (micro-ARPES) have enabled my group to overcome key aspects of these barriers. Our investigation provides a direct window into the electronic interactions and symmetries that define the TKI state, including critical information to explain the phenomenal robustness of topological and insulating properties against profound disorder (up to ~50% alloying). The talk will include a broad introduction to the TKI state and its associated phenomenology.
L. Andrew Wray is Assistant Professor of Physics. He holds a Ph.D. in Experimental Condensed Matter Physics from Princeton University (2010) and a B.A. in Physics from the University of California, Berkeley, and conducted pre-doctoral research at the Institute of Physics, Chinese Academy of Sciences. After completing his Ph.D., Wray led research projects at the Lawrence Berkeley National Laboratory (LBNL) and Stanford Institute for Materials and Energy Sciences (SIMES) prior to joining the NYU faculty in 2014.
Wray’s research focuses on the discovery, characterization and manipulation of novel quantum states inside materials. His experiments have been instrumental in identifying the first realizations of topologically ordered quantum states of matter such as the topological insulator and topological superconductor. Incisive in-situ investigation of the energy and momentum profiles of quantum states is made possible by rapidly advancing capabilities at state of the art X-ray facilities. Wray maintains active involvement in proposing new X-ray science technologies and developing novel methods to simulate and analyze resonant interactions between X-rays and matter.
Seminar by the NYU-ECNU Institute of Physics at NYU Shanghai