题目

Flat-Band Materials

报告人

Prof. Feng Liu

Department of Materials Science & Engineering,

University of Utah, USA

时间

2018年10月23日（星期二）上午10：00

地点

微尺度国家研究中心9004会议室

刘锋，材料物理学家，美国犹他大学材料系终身教授、系主任，美国物理学会会士(APS Fellow)，物理评论快报编辑(PRL Divisional Associate Editor)。曾获德国洪堡高级研究奖，澳大利亚国际教授奖，中国基金委海外杰青奖等。刘锋教授主要从事应变薄膜纳米自主装，石墨烯，拓扑材料的基础和应用研究。已发表280多篇学术论文。另外，刘锋教授还是10多项专利的发明人。2011年，刘锋教授的团队发明了纳烯(Nanoxene)复合材料并创办了Life-E公司，目前正在开拓纳烯材料技术在电热产品中的应用。

报告摘要

Unlike a localized state induced by defect in a crystalline solid, the so-called flat band is truly a Bloch state but yet without band dispersion. It arises from destructive interference of Bloch wave functions, independent of the single-particle crystalline Hamiltonian (i.e., the strength of lattice hopping). Flat band can host a range of exotic quantum phases, such as ferromagnetism, Wigner crystallization, superconductivity and high-temperature fractional quantum Hall effect. In this talk, I will first briefly review lattice models which give rise to 2D/3D flat bands including a new Coloring-Triangle lattice we found recently. I will then discuss real flat-band materials including our recent work on pyrochlore Sn₂Nb₂O₇ which hosts 3D flat bands. A novel mechanism for the formation of Weyl points enabled by doping of doubly degenerated 3D flat bands, instead of symmetry breaking of a Dirac point, will also be discussed.