Nonreciprocal responses in noncentrosymmetric hybrid superconductors

In recent years, various phenomena, including the superconducting diode effect (SDE) in which superconducting current flows only in the forward direction, have been observed in noncentrosymmetric superconductors. Recent experiments have demonstrated zero-field SDE, in which current rectification occurs without an external magnetic field. The zero-field SDE can be effectively controlled by utilizing the proximity effect at the superconducting/ferromagnetic interface. Zero-field SDEs have the potential to realize new nonvolatile memory devices and logic circuits with ultra-low power consumption. Here, we report the magnetization control of nonreciprocal critical current in superconducting multilayers without time-reversal and spatial-inversion symmetries. When the magnetization directions of the ferromagnetic layers above and below the superconducting layer are parallel, the nonreciprocal critical current becomes finite. However, when the magnetization directions are antiparallel, the nonreciprocal critical current becomes zero. This feature enables the control of zero-field SDE that is enabling polarity reversal and on/off switching. These findings open avenues for formulating design guidelines for noncentrosymmetric hybrid superconductors.