标题： 零磁场下某些二维超导体中的反对称手征电流 显示英文标题

标题： Anti-symmetric Chiral currents at zero magnetic field in some two-dimensional superconductors

摘要： 在没有施加外部磁场的情况下，最近在几种超导体中观察到了非互易临界电流，包括石墨烯、Kagome化合物以及欠掺杂铜氧化物的不同形式。 这种现象的一个必要条件是，通常的超流电流必须伴随着反称手性超流电流，即具有霍尔电流的对称性；或者等效地，超流密度张量必须具有反称手性分量。 此外，还需要破缺空间反演对称性。 推导出该现象的条件后发现，其正常态必须破缺时间反演对称性和手性，而超导态还必须是非幺正的。 在所有观察到自发非互易临界电流的超导体中，其正常态都显示出这些对称破缺的证据。 这类材料的超导态具有拓扑边缘电流，但其投影的电磁部分通常不是整数。 由于存在能隙，边缘态在超导体中受到保护。 正常态应表现出Kerr效应，并且在理想条件下，还应表现出反常霍尔效应。 显示英文摘要

摘要： Non-reciprocal critical currents without applying an external magnetic field have been observed recently in several superconductors, in various forms of Graphene, a Kagome compound and in an under-doped cuprate. A necessary requirement for this is that the usual supercurrent be accompanied by an anti-symmetric chiral super-current, i.e. with the symmetry of a hall current; equivalently that the superfluid density tensor have an anti-symmetric chiral component. It also requires inversion breaking. The conditions for this phenomena are derived to find that their normal states must break time-reversal and chirality and that the superconducting states must in addition be non-unitary. Each of the superconductors where spontaneous non-reciprocal critical currents are observed have shown some evidence for such broken symmetries in the normal state. The superconducting state of such materials have topological edge currents, but their projected electro-magnetic part is in general not an integer. The edge states are protected in the superconductor due to a gap. The normal state should show a Kerr effect and, under ideal conditions, an anomalous Hall effect.