We derive an approximate energy barrier equation considering its adaptation to our model calculation employing the Néel-Arrhenius model with the Stoner-Wohlfarth grain or dot in magnetic recording. First, we calculate the energy barrier as a function of magnetic field by employing a numerical calculation for an angle of 0 to 180 deg between an easy axis and the magnetic field. This relation is represented by an approximate equation for an angle of 0 to 90 deg, taking account of Pfeiffer’s approximation for an angle of 90 to 180 deg. Next, the shape anisotropy energy for a cuboid or cylinder is also represented by an approximate equation, since the energy barrier is a function of the shape anisotropy energy.

  The superconducting diode effect in which electrical resistance is zero in only one direction has recently been reported in superconductors without inversion symmetry. Previous studies investigated the nonreciprocity of the critical current, but little has been known about the rectification effect when AC currents are applied. Herein, we examined the rectification characteristics of a non-centrosymmetric Nb/V/Ta artificial superlattice under AC currents. The rectification strength can be modulated by an applied magnetic field, and its polarity can be tuned by the magnetic field. Furthermore, we find that the magnetic field dependence of the rectification is different from that of the nonreciprocal critical current.