Nonreciprocal transport effects can occur in the normal state of conductors and in superconductors when both inversion and time-reversal symmetry are broken. Here, we consider systems where magnetochiral anisotropy of the energy spectrum due to an externally applied magnetic field results in a rectification effect in the normal state and a superconducting (SC) diode effect when the system is proximitized by a superconductor. Focusing on nanowire systems, we obtain analytic expressions for both normal state rectification and SC diode effects that reveal the commonalities—as well as differences—between these two phenomena. Furthermore, we consider the nanowire brought into an (almost) helical state in the normal phase or a topological SC phase when proximitized. In both cases, this reveals that the topology of the system considerably modifies its nonreciprocal transport properties. Our results provide insights into how to determine the origin of nonreciprocal effects and further evince the strong connection of nonreciprocal transport with the topological properties of a system.

中文翻译：

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平凡相和拓扑相中正常态不可逆输运与超导二极管效应之间的关系


当反演对称性和时间反转对称性都被破坏时，在正常状态的导体和超导体中可能会发生不可逆输运效应。在这里，我们考虑由于外部施加的磁场而导致能谱的磁手性各向异性的系统，导致正常状态下的整流效应和当系统接近超导体时的超导（SC）二极管效应。重点关注纳米线系统，我们获得了常态整流和 SC 二极管效应的解析表达式，揭示了这两种现象之间的共性和差异。此外，我们认为纳米线在正相中进入（几乎）螺旋状态，或者在接近时进入拓扑 SC 状态。在这两种情况下，这表明系统的拓扑极大地改变了其不可逆传输属性。我们的结果为如何确定不可逆效应的起源提供了见解，并进一步证明了不可逆输运与系统拓扑特性的紧密联系。