Perfect spin Josephson diode effect in unconventional p-wave magnet

¹ College of Physics, Nanjing University of Aeronautics and Astronautics - Nanjing 211106, China
² Key Laboratory of Aerospace Information Materials and Physics (NUAA), MIIT - Nanjing 211106, China

Received: 8 October 2025
Accepted: 20 February 2026

Abstract

We propose a mechanism for a spontaneous spin Josephson diode effect (JDE) without an external magnetic field, based on an unconventional p-wave magnet (UPM) with spin-orbit coupling (SOC). In this S/N/UPM/N/S Josephson junction, the UPM provides an intrinsic equal-spin triplet pairing channel, while the interfacial SOC breaks spatial inversion symmetry, endowing Cooper pairs of different spin components with opposite phase gradients. Under zero external magnetic field while time-reversal symmetry is preserved, the charge Josephson diode effect vanishes, whereas the spin rectification efficiency can reach the theoretical limit for ideal parameters —corresponding to a perfect spin rectification where the spin supercurrent in one direction is allowed, but it is blocked in the other direction. Our results propose a new strategy for achieving highly efficient spin JDE, endowing Josephson-junction–based quantum devices with new functionalities.