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Description
The p-n junction diode is a cornerstone of electronics, but its rectification is intrinsically dissipative. Recently, its superconducting analogue, the Josephson diode effect (JDE), characterised by unequal critical currents in opposite directions in Josephson junction (JJ), has been observed experimentally and predicted theoretically in models of planar JJs. Realising JDE typically requires breaking both time reversal and inversion symmetry, which is often implemented using external magnetic field or incorporating ferromagnetic materials. However, these approaches introduce stray fields and magnetic cross-talk, posing a significant obstacle for device integration.\
Here we establish a field-free route using unconventional magnets namely, altermagnet \cite{reference1} and p-wave magnet \cite{reference2}. These magnets break time reversal symmetry (TRS) while maintaining zero magnetisation. We demonstrate that the mere breaking of time-reversal and inversion symmetry is not sufficient to guarantee a diode effect. We have provided necessary conditions for the diode effect using altermagnet as barrier in JJ without using external field. The diode effect is also shown to be tunable using gate potential, change polarity and increasing non-reciprocity, offering a simple experimental knob for control.
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Using p-magnet in proximity s-wave SC as the leads of JJ, with AM as barrier we also shown that we do not require Rashba SOC, which was emphasised in previous theoretical proposals. Moreover in both type of junction the efficiency of diode effect is reached about 45%.