论文标题
拓扑量量量子化学的锁定锁定:多胎费用的应用
Spin-momentum locking from topological quantum chemistry: applications to multifold fermions
论文作者
论文摘要
在自旋轨道耦合晶体中,对称性可以保护具有较大Chern数字的多重变性和跨越拓扑表面状态的Brillouin区域。在这项工作中,我们探讨了手性多胎费用的非平凡拓扑影响散装状态的自旋纹理。为此,我们根据降低的密度矩阵制定了自旋摩托明锁定的定义。使用拓扑量子化学理论中的工具,我们展示了如何从轨道轨道的知识和构成多重速度费米子的基础轨道和带状表示的知识中确定降低的密度矩阵。我们展示了现场旋转轨道耦合,晶体场分裂和Wyckoff位置多样性如何竞争,以确定手性费米子附近状态的自旋纹理。我们在空间群体的几个代表性示例中计算了多胎费米的旋转质地$ P432 $(207)和$ p2_13 $(198)。我们表明,费米表面周围的旋转数量可能需要许多不同的整数值,从零到$ \ pm 7 $。最后,我们结论是通过在太空群中使用PTGA的示例来展示如何将我们的理论应用于真实材料$ p2_13 $。
In spin-orbit coupled crystals, symmetries can protect multifold degeneracies with large Chern numbers and Brillouin zone spanning topological surface states. In this work, we explore the extent to which the nontrivial topology of chiral multifold fermions impacts the spin texture of bulk states. To do so, we formulate a definition of spin-momentum locking in terms of reduced density matrices. Using tools from the theory of topological quantum chemistry, we show how the reduced density matrix can be determined from the knowledge of the basis orbitals and band representation forming the multifold fermion. We show how on-site spin orbit coupling, crystal field splitting, and Wyckoff position multiplicity compete to determine the spin texture of states near chiral fermions. We compute the spin texture of multifold fermions in several representative examples from space groups $P432$ (207) and $P2_13$ (198). We show that the winding number of the spin around the Fermi surface can take many different integer values, from zero all the way to $\pm 7$. Finally, we conclude by showing how to apply our theory to real materials using the example of PtGa in space group $P2_13$.