Hysteretic Supercurrent and Trivial Zero-bias Peaks at Zero External Magnetic Field Due to Stray Fields from Micromagnets in Sn-InSb and Al-InAs Nanowire Junctions

Superconductor-semiconductor-superconductor and superconductor-semiconductor junctions fabricated from InSb and InAs nanowires attract attention in recent years. InSb and InAs nanowires are though to have strong spin orbit interaction and high mobility; coupled with superconductivity, these wires are believed to be appropriate platforms for Majorana bound states. In experiments, specific parameter combinations of chemical potentials and magnetic fields may create states inside superconductor induced gaps. A zero-bias peak of differential conductance sometimes appear, which is a signature of Majorana bound states. In our experiments, we placed micromagnets close to Sn-InSb-Sn junctions and Al-InAs junctions. Magnetized micromagnets produced local magnetic fields penetrating the devices and we observed hysteretic supercurrents in Sn-InSb-Sn junctions and hysteretic Andreev bound states in Al-InAs junctions. At zero external magnetic field and with finite local magnetic fields, zero-bias peaks due to trivial Andreev bound states were observable. The interpretation of our zero-bias data does not require existence of Majorana bound states.