Tunneling spectroscopy in InSbAs-Al multi-probe devices

Majorana zero modes can emerge as edge states in a one-dimensional topological superconductor.The primary experimental approach for identification is an emerging zero-bias peaks (ZBPs) in tunneing spectroscopy at the edge of the system, which, however, can also be due to many trivial origins. A more unique (and thus strong) accompanying signature is the re-opening of the bulk superconducting gap. Some initial attempts have been done on the mostly studied nanowire platform, where it requires some sophisticated fabrication steps .Here we study the electron transport of the quasi-1D structures made from the new InSbAs2DEGs-Al system, where the semiconductor shows very strong spin-orbit interaction. In addition, the inherent design flexibility allows for a straightforward realization of multiple tunnel junctions along the 1D strip. By using tunneling spectroscopy, we study both the local energy spectra simultaneously at different positions, and also the non-local responses of individual sections. At zero magnetic field, locally we have observed the hard superconducting gap with same gap size along the wire, indicating a uniform proximity over μm-long length scale. The superconducting gap becomes smaller and eventually close at in-plane field B≈1.1 T, after which zero bias peaks emerge at tunnel probes located at the edges, while this is less prominent for probes in the bulk. At similar magnetic field, a sign flip of the non-local conductance has also been repeatedly observed.