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2017-05-18 Chiral symmetry classes and spiraling Dirac nodal lines in three-dimensional layered systems 何青峰 博士(台南應用科技大學)
Chiral symmetry classes and spiraling Dirac nodal lines in three-dimensional layered systems
 

Speaker : Dr. Ching‐Hong Ho 何青峰 博士  (Tainan University of Technology 台南應用科技大學)

Time : 2017/05/18 (Thu.) 13:20~15:10

Place : SC001 (次軒廳), Science Building III, NCTU.

Host : Prof. Shun-Jen Cheng 鄭舜仁教授

Abstract : The topological properties of a physical system are generally dictated by a certain global topological number, which can be invariant against perturbation or disorder under specific constraints so that the system is in a nontrivial topological phase. According to the topological classification scheme developed for decades, the topological invariants are determined by the symmetry classes of the Hamiltonians and the spatial dimensions. Among the gapped phases in, say, topological insulators, gapless phases in topological semimetals and nodal semiconductors have attracted much interest recently. Here, we discuss the chiral symmetry classes owing to bi-particle lattice ranging from 2D to 3D, for the possibility of 3D topological semimetals obtained from the layer stack of 2D lattices. We focus on whether or not there are nontrivial Dirac nodal lines in the 3D band structure if there are nontrivial Dirac nodal points in 2D.