Kagome Magnet RMn6Sn6: First-principles study
演講者 : 田鴻儒 博士生 (成功大學物理系)
演講地點 : 理學教學新大樓物理系 5F 36567會議室
演講時間 : 2021 / 11 / 17 16:20
Kagome lattice is a two-dimensional honeycomb structure network with triangular corner sharing. The band structure of kagome lattice has been theoretically predicted to possess both flat bands and Dirac states in the Brillouin zone. In addition, the band degeneracy will be lifted and present a topological nontrival gap as considering time-invariant intersite spin-orbit coupling. Recently, a new kagome family RMn6Sn6 has been found to provide a tunable magnetic configuration by replacing different rare earth elements R. For example, TbMn6Sn6 (R=Tb) shows a ferrimagnetic state with our-of-plane spin orientation. Based on first-principles calculations, we identify a highly orbital-selective massive Dirac state forming by Mn dx2-y2/dxy with 35 meV large energy gap at K point, which is well consistent with our tunneling measurement . Remarkably, our calculation exhibits the strong Berry curvature in this gapped Dirac state, supporting TbMn6Sn6 may be an intrinsic Chern insulator. Besides TbMn6Sn6, we find an in-plane spin configuration in GdMn6Sn6. Via Our first-principles calculations demonstrate a tunable gap via changing the magnetic configuration. Experimentally, through doping the Tb atoms in GdMn6Sn6, the out of plane magnetic configuration can be realized. Our calculation reveals an orbital-selective and a tunable topological gap in kagome magnet RMn6Sn6 and provide a natural platform to investigate the interplay between topology and magnetism.