物理系徐剛學術報告的通知(Physics Department Colloquium)

編輯:江丹 來源:物理學系 時間:2019年11月05日 訪問次數:0  源地址

題目:Some exotic topological states in Magnetic groups

報告人:徐剛 華中科技大學國家脈沖強磁場科學中心

地點: 教十二—201

時間: 118日,周五,15:30-16:30



In Magnetic groups (MGs), the time reversal symmetry is broken, but its combinations with some crystalline symmetries, named as crystalline time reversal symmetry (CTRS), are preserved, and can protect the novel topological phase against the local perturbations without destroy the magnetic symmetries. In this talk, I will introduce two works on the exotic topological quantum states in magnetic groups. 1. Antiferromagnetic (AFM) Dirac semimetals (DSMs) realized in the interlayer AFM EuCd2As2. In this work, we generalize the concept of DSM to the magnetic space groups (MSGs), and define a new category of DSM in type IV MGs. Many exotic topological states, such as the triple point semimetal and the AFM topological insulator holding of the half-quantum Hall effect can be derived from such AFM DSMs by breaking certain symmetry, providing an ideal platform to study topological phase transitions. 2. New type of topological superconductor (TSC) phase in the 1-dimensional (1D) MGs. We find that the CTRS could enrich the classification of TSC. In the 1D system generated by  or  symmetry, such CTRS could lead to the BDI class of TSC with  topological invariant, rather than the conventional D- or DIII-class (Z2 invariant). More interestingly, the TSC phase in the MGs generated by  and  are totally beyond the Altland and Zirnbauer symmetry classes, but belong to a new type of  ( for  system) classification, in which the robust Majorana zero modes are protected by the unitary chiral symmetry. The minimal tight binding BdG Hamiltonians satisfying  or  MGs are also constructed to illustrate the novel TSC phase.



徐剛,華中科技大學教授,博士生導師,青年千人計劃入選者。2010年獲中國科學院物理研究所博士學位,2010-2012年任中科院物理所助理研究員,2012-2016在美國斯坦福大學做訪問研究,20169月至今在華中科技大學國家脈沖強磁場中心工作。2017年入選中組部第十三批千人計劃“青年項目”。2018年獲科技部重點研發計劃青年項目(項目負責人);獲“2018年度中國科學院杰出科技成就獎(集體)”。主要從事新奇物性和材料的第一性原理計算和理論研究。研究興趣包括:強關聯與非常規超導、拓撲物質態,新型二維功能材料等,已發表學術論文40多篇,其中Nature子刊、PRL等國際頂級期刊17篇,另有兩篇論文入選“2008年中國百篇最具影響國際學術論文”;總引用6000多次, H因子27



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