Speaker: Shiming Lei, Princeton University
Program Description:
Topological materials have been the source of many exciting new discoveries. Despite the rapid advances achieved by the development of high throughput materials search program, many known topological materials suffer from non-ideal band structures. For example, topological bands are frequently convoluted with trivial ones, and band structure features of interest can appear far below the Fermi level. One strategy to achieve "better" topological materials has been chemical doping which can shift the chemical potential to the points of interest. This strategy, however, does not help to remove interfering bands from the Fermi level. In this talk, I will introduce a new strategy to design nearly idealized topological semimetals. Two vital ingredients for this strategy will be discussed: a charge density wave (CDW), which gaps out the unwanted states at the Fermi level, and the non-symmorphic symmetry, which enforces Dirac nodes. I will further show the experimental verification of this strategy by synthesizing single crystals of the non-symmorphic CDW material GdSb0.46Te1.48 and studying the electronic structure with angle-resolved photoemission spectroscopy (ARPES). Not only are the theoretical and experimental band structure in good agreement, but GdSb0.46Te1.48 also exhibits complex magnetism and highly unusual transport behaviors, which point to the realization of a new transport regime deserving of further investigation.
