Time-reversal-invariant topological superconductivity in doped Weyl semimetals
Time-reversal-invariant topological superconductivity in doped Weyl semimetals
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DOI：
10.1103/physrevb.90.045130
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发表时间：
2014-07-24
影响因子：
3.7
通讯作者：
Qi, Xiao-Liang
中科院分区：
文献类型：
--
作者：
Hosur, Pavan;Dai, Xi;Qi, Xiao-Liang
逆时不变拓扑超导体是一种具有大块超导间隙和稳健的马约拉纳费米子表面态的新型物质态。这些还没有在固态系统中实现。在本文中，我们提出这种状态可以在掺杂Weyl半金属或Weyl金属中实现。Weyl金属的费米表面携带陈恩数，这是这种拓扑超导体的必要成分。通过将波动交换方法应用于时间反转不变Dirac和Weyl半金属的一般模型，我们研究了什么微观相互作用可以提供其他成分，即具有相反chen数的费米表面之间超导间隙函数的符号变化。我们发现，如果正态是反转对称的，则现场排斥和交换相互作用会在相图上诱导出各种节点相以及小区域的拓扑超导性。与He-3-B拓扑超导体不同，这里的相位不依赖于配对振幅的任何特殊动量依赖。打破反转对称排除了一些节点相，拓扑超导体变得更加突出，特别是在大铁磁相互作用中。我们的方法可以扩展到一般的狄拉克或Weyl金属。
Time-reversal-invariant topological superconductors are a new state of matter which have a bulk superconducting gap and robust Majorana fermion surface states. These have not yet been realized in solid state systems. In this paper, we propose that this state can be realized in doped Weyl semimetals or Weyl metals. The Fermi surfaces of a Weyl metal carry Chern numbers, which is a required ingredient for such a topological superconductor. By applying the fluctuation-exchange approach to a generic model of time-reversal-invariant Dirac and Weyl semimetals, we investigate what microscopic interactions can supply the other ingredient, viz., a sign change of the superconducting gap function between Fermi surfaces with opposite Chern numbers. We find that if the normal state is inversion symmetric, on-site repulsive and exchange interactions induce various nodal phases as well as a small region of topological superconductivity on the phase diagram. Unlike in the He-3-B topological superconductor, the phase here does not rely on any special momentum dependence of the pairing amplitude. Breaking inversion symmetry precludes some of the nodal phases and the topological superconductor becomes much more prominent, especially at large ferromagnetic interaction. Our approach can be extended to generic Dirac or Weyl metals.