Josephson diode effect in asymmetric junctions with nonsinusoidal current–phase relation near Tc

This study theoretically investigates the influence of anharmonicity of the current–phase relation on the properties of Josephson junctions with broken spatial symmetry of the critical current density distribution. Specifically, we consider a model of a superconducting tunnel junction of the superconductor–insulator–superconductor type under conditions where depairing effects play a significant role, resulting in a nonsinusoidal current–phase relation. It is demonstrated that in the short junction approximation, the combination of asymmetry in the critical current density profile and anharmonicity of the current–phase relation constitutes a sufficient condition for the emergence of the Josephson diode effect. We obtain the dependence of the diode effect efficiency on the anharmonicity and asymmetry parameters. Furthermore, we find that, in contrast to the sinusoidal case, the considered model exhibits substantial magnetic-field-dependent nonreciprocity, which can serve as an indicator of microscopic current transport mechanisms.