论文标题
超导轨道磁电效应及其在超导性正常金属相变
Superconducting Orbital Magnetoelectric Effect and its Evolution across the Superconductivity Normal Metal Phase Transition
论文作者
论文摘要
超导磁电效应是超导体中电流诱导的磁化强度，在先前的研究中主要集中于自旋磁化，但忽略了配对的Bloch电子携带的轨道磁矩的作用。在这项工作中，我们表明超导体中的轨道磁矩可以在存在电流的情况下诱导大轨道磁化。我们构建了一个统一的描述，用于跨超导率正常金属相变的电流诱导的自旋和轨道磁化。我们发现，在具有均匀配对的超导体中，在给定电流密度下的电流诱导的磁化与其正常金属状态相同，而在非均匀的超导配对的情况下，电流诱导的磁化强度在超导性金属相位过渡的幅度上显示出突然的幅度变化。重要的是，我们的理论预测了超导扭曲的双层石墨烯中的轨道磁电效应，后者将Bloch电子与大轨道磁矩和可忽略不计的旋转轨道耦合配对。我们提出，可以使用电流诱导的轨道磁电效应的测量来检测扭曲的双层石墨烯和其他具有非平凡浆果曲率的新发现的超导体中可能的非均匀配对。
Superconducting magnetoelectric effect, which is the current-induced magnetization in a superconductor, mainly focused on the spin magnetization in previous studies, but ignore the effect of the orbital magnetic moments carried by the paired Bloch electrons. In this work, we show that orbital magnetic moments in superconductors can induce large orbital magnetization in the presence of a current. We constructed a unified description for the current-induced spin and orbital magnetization across the superconductivity normal metal phase transition. We find that in a superconductor with uniform pairing, the current-induced magnetization at a given current density is the same as that in its normal metal state, while with the nonuniform superconducting pairing, the current-induced magnetization exhibits an abrupt change in magnitude near the superconductivity normal metal phase transition. Importantly, our theory predicts the orbital magnetoelectric effect in superconducting twisted bilayer graphene which has paired Bloch electrons with large orbital magnetic moments and negligible spin-orbit coupling. We propose that the measurement of the current-induced orbital magnetoelectric effect can be used to detect the possible nonuniform pairings in twisted bilayer graphene and other newly discovered superconductors with non-trivial Berry curvatures.
