Spin-momentum locking from topological quantum chemistry: Applications to multifold fermions
Spin-momentum locking from topological quantum chemistry: Applications to multifold fermions
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DOI：
10.1103/physrevb.106.245101
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发表时间：
2022-04
影响因子：
3.7
通讯作者：
Mao Lin;I. Robredo;N. B. M. Schröter;C. Felser;M. Vergniory;B. Bradlyn
中科院分区：
文献类型：
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作者：
Mao Lin;I. Robredo;N. B. M. Schröter;C. Felser;M. Vergniory;B. Bradlyn
在自旋轨道耦合晶体中，对称性可以保护多重简并与大陈数和布里渊区跨越拓扑表面态。在这项工作中，我们探讨了手征多重费米子的非平凡拓扑结构对体态自旋织构的影响程度。为此，我们用约化密度矩阵来定义自旋-动量锁定。使用拓扑量子化学理论的工具，我们展示了如何从形成多重费米子的基轨道和能带表示的知识中确定约化密度矩阵。我们展示了如何现场自旋轨道耦合，晶体场分裂，和Wycko的位置多重竞争，以确定附近的手征费米子的自旋纹理的状态。我们计算了P432（207）和P213（198）空间群中几个有代表性的多重费米子的自旋织构。我们证明了自旋绕费米面的缠绕数可以取许多不同的整数值，从零一直到± 7。最后，我们总结了如何将我们的理论应用到真实的材料使用的例子PtGa在空间群P2 1 3。
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 P 432 (207) and P 2 1 3 (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 ± 7. Finally, we conclude by showing how to apply our theory to real materials using the example of PtGa in space group P 2 1 3.