Phase-controlled perfect nonlocal spin and charge diode effects in a four-terminal Josephson junction with $p$-wave magnets
We theoretically investigate charge and spin transport in a four-terminal Josephson junction with a normal-metal barrier. The top and bottom superconducting leads are equal-spin triplet $p_y$-wave superconductors, while the left and right leads are $p$-wave magnets with proximity-induced conventional $s$-wave superconductivity. When the transverse macroscopic phase difference between the top and bottom leads is set to zero, a longitudinal phase bias generates a pure transverse spin current with perfect 100% nonreciprocity. Remarkably, a finite transverse phase difference preserves the perfect spin-diode effect while simultaneously inducing a perfect charge-diode effect, enabling fully nonreciprocal spin and charge transport. Moreover, the spin-diode efficiency exhibits sharp, step-like switching as a function of both the gate voltage applied to the barrier and the crystallographic orientation of the $p$-wave magnet, providing independent and experimentally accessible knobs for controlling the diode polarity. The diode response remains robust against asymmetric interface couplings, nonmagnetic disorder, variations in the relative singlet and triplet pairing strengths, temperature, and junction dimensions, demonstrating that the effect is not a consequence of fine-tuned parameters. These findings establish the proposed four-terminal junction as a highly tunable and structurally robust platform for dissipationless, phase-controlled spin and charge rectification, with potential applications in superconducting spintronics.