Nakai Hiroki, Hotta Chisa
Department of Basic Science, University of Tokyo, Meguro-Ku, Komaba 3-8-1, Tokyo, 153-8902, Japan.
Nat Commun. 2022 Feb 1;13(1):579. doi: 10.1038/s41467-022-28132-y.
Spin-orbit interaction has established itself as a key player in the emergent phenomena in modern condensed matter, including topological insulator, spin liquid and spin-dependent transports. However, its function is rather limited to adding topological nature to band kinetics, leaving behind the growing interest in the direct interplay with electron correlation. Here, we prove by our spinor line graph theory that a very strong spin-orbit interaction realized in 5d pyrochlore electronic systems generates multiply degenerate perfect flat bands. Unlike any of the previous flat bands, the electrons in this band localize in real space by destructively interfering with each other in a spin selective manner governed by the SU(2) gauge field. These electrons avoid the Coulomb interaction by self-organizing their localized wave functions, which may lead to a flat-band state with a stiff spin chirality. It also causes perfectly trimerized charge ordering, which may explain the recently discovered exotic low-temperature insulating phase of CsWO.
自旋轨道相互作用已成为现代凝聚态物质中涌现现象的关键因素，这些现象包括拓扑绝缘体、自旋液体和自旋相关输运。然而，其作用相当有限，仅为能带动力学增添拓扑性质，而对与电子关联的直接相互作用的兴趣却与日俱增。在此，我们通过旋量线图理论证明，在5d焦绿石电子系统中实现的非常强的自旋轨道相互作用会产生多重简并的完美平带。与之前的任何平带不同，该能带中的电子通过在由SU(2)规范场控制的自旋选择性方式下相互相消干涉而在实空间中局域化。这些电子通过自组织其局域波函数来避免库仑相互作用，这可能导致具有刚性自旋手性的平带态。它还会导致完美的三聚体电荷有序，这可能解释了最近发现的CsWO的奇异低温绝缘相。
