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Topological Semimetals: How to find them

日程 : 2017年12月14日(木) 16:00 - 17:00 場所 : 物性研究所本館6階 大講義室(A632) 講師 : Prof. Hongming Weng 所属 : Institute of Physics, Chinese Academy of Sciences and Collaborative Innovation Center of Quantum Matter 世話人 : 談話会委員:杉野 修 ・ 長谷川 幸雄
e-mail: danwakai@issp.u-tokyo.ac.jp

In this talk, I will introduce the family of topological semimetals (TSM) including Dirac semimetal (DSM), Weyl semimetal (WSM), and triply degenerate nodal point semimetal (TPSM). In ideal case, they have and only have nodal points at the Fermi level, but they are classified according to the distribution and degeneracy of these nodal points. The quasiparticles of low energy excitation in DSM and WSM can be described by massless Dirac and Weyl equation, respectively, while those in TPSM have no counterpart in the high-energy field theory. To find realistic materials hosting these exotic topological quantum states is very challenge and crucial to the further experimental studies. We noticed that the unusual temperature dependent diamagnetism is a strong hint of existence of linear Dirac cone like bands around Fermi level. This has been confirmed in DSMs Na3Bi and HfTe5 at phase transition. It also leads to the success in locating TaAs, the first available WSM. The experimental studies of these materials have stimulated many research works, including the characteristic chiral anomaly and Fermi arcs. Finally, the TSM family members and their relationship with each other are summarized.

最近の話題のテーマであるワイル半金属について理解を深める良い機会ですので、 是非、皆様ご参加ください。

(公開日: 2017年11月30日)