We report that the superconducting critical magnetic field can be nonreciprocal under a bias of an electric current in a superconducting [Nb/V/Ta] _n superlattice without a center of inversion. The critical magnetic field showed a clear difference between positive and negative magnetic fields. Furthermore, the magnitude relation between the positive and negative critical magnetic fields is reversed when the direction of the electric current is reversed. Our findings indicate that the superconducting gap can be anisotropic by the application of an electric current.

中文翻译：

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非互易超导临界场的观测

我们报告说，超导临界磁场在没有反转中心的超导 [Nb/V/Ta] _n超晶格中的电流偏置下可以是非互易的。临界磁场表现出明显的正负磁场差异。此外，当电流方向反转时，正负临界磁场之间的大小关系也反转。我们的研究结果表明，通过施加电流，超导间隙可以是各向异性的。