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Valley contrasting chiral phonons in monolayer hexagonal lattices

来源：
报告题目   Valley contrasting chiral phonons in monolayer hexagonal lattices
报告人   Prof. NIU Qian
报告人单位   University of Texas at Austin, USA & Peking University
报告时间   2015-01-13
报告地点   合肥微尺度物质科学国家实验室九楼会议室（9004室）
主办单位   合肥微尺度物质科学国家实验室、国际功能材料量子设计中心
报告介绍
Abstract:
　　In monolayer haxagonal lattices, two inequivalent valleys appear in the Brillouin zone. With inversion symmetry breaking, we find chiral phonons with valley contrasting polarization and ionic magnetic moment. At valley centers, there is a three-fold rotational symmetry endowing phonons with a quantized pseudo angular momentum, which includes spin and orbital parts. From conservation of the pseudo angular momentum, crystal momentum and energy, selection rules in intervalley scattering of electrons by phonons are obtained. Due to chiral valley phonons, one can also observe polarized infrared photoluminescence and a valley phonon Hall effect induced by a valley contrasting phonon Berry curvature.

Biosketch:
　　Professor Qian Niu obtained a B.S. from Peking University in 1981. He went to the University of Washington for graduate studies, and received his Ph.D. in physics in 1985. Now he is a Trull Centennial Professor of Physics at the University of Texas at Austin, from which he is currently on leave to serve as the director of the International Center for Quantum Materials at Peking University. He has worked on the theories on quantum Hall effects, quasicrystals, ultracold atoms, spin transport, and graphene materials, with an emphasis on topological and geometric phase effects in quantum transport. He has published more than 220 peer reviewed papers, including 70 in Physical Review Letters, and has over 12000 citations (with an H index of 58).

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