Superconducting diode effect in InAs/Al Josephson junctions at high in-plane magnetic fields

Nonreciprocal critical current in superconducting Josephson junctions occurs when the critical current I_c depends on the direction the current was swept and can be observed by breaking the time reversal and inversion symmetries in the system. Recently, there has been a surge of interest in studying the superconducting diode effect due to its possible application in electronic circuits, sensors, and detectors. In this work, we study epitaxial InAs/Al Josephson junctions with various superconductor width in the presence of in-plane magnetic fields. By applying a magnetic field parallel to the junction, we observe nonreciprocal critical current which is due to the strong Rashba spin-orbit interaction in the system. However, by reducing the width of the superconducting lead, we observe a change in sign of ΔI=I(+)-I(-) as we increase the in-plane magnetic field. We discuss the possible mechanisms and possibility of finite momentum pairing.