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arXiv 1506.05166cond-mat.supr-concond-mat.mes-hall
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超导体和自旋活性材料周期结构中的Weyl节点

Weyl nodes in periodic structures of superconductors and spin active materials

Ahmet Keles, Erhai Zhao

摘要:

受s波超导体(S)和自旋激活材料(M)邻近结构外延生长的最新进展的启发,我们证明了S和M的周期结构可以有效地表现为具有点节点对的超导体,在点节点附近的低能激发是Weyl费米子。本文提出了一个简单的玩具模型,其中M由具有自旋-轨道耦合和交换场的Kronig-Penney势描述,并求解该模型,得到了节点结构的相图、Weyl费米子的自旋织构以及以开费米线(“费米弧”)形式出现的零能表面态。超越简单模型,求解了具有S和磁性$Z_2$拓扑绝缘体(M)的交替层的晶格模型。计算的光谱证实了以前的预测的Weyl节点的基础上的狄拉克电子的隧穿哈密顿量。我们的研究结果提供了进一步的证据,S和M的周期性结构是非常适合工程无带隙拓扑超导体。

英文摘要:

Motivated by recent progress in epitaxial growth of proximity structures of s-wave superconductors (S) and spin-active materials (M), we show that the periodic structure of S and M can behave effectively as a superconductor with pairs of point nodes, near which the low energy excitations are Weyl fermions. A simple toy model, where M is described by a Kronig-Penney potential with both spin-orbit coupling and exchange field, is proposed and solved to obtain the phase diagram of the nodal structure, the spin texture of the Weyl fermions, as well as the zero energy surface states in the form of open Fermi lines ("Fermi arcs"). Going beyond the simple model, a lattice model with alternating layers of S and magnetic $Z_2$ topological insulators (M) is solved. The calculated spectrum confirms previous prediction of Weyl nodes based on tunneling Hamiltonian of Dirac electrons. Our results provide further evidence that periodic structures of S and M are well suited for engineering gapless topological superconductors.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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