Superconducting gap closing and Zero-bias peak in InSb nanowire

In a 1D superconductor-nanowire-normal contact system, Majorana bound states are expected to appear after topological phase transition. Although there are many experiments reported possible zero-bias conductance peak from Majorana bound states, mapping out of the topological phase diagram is still missing.In our InSb nanowire hybrid devices, we observed possible superconducting gap closing and re-opening with magnetic field. These gap closings appear near conductance resonances which show some feature of 1D subband edges. Interestingly, zero-bias conductance peak appears inside the split regime of crossings at finite magnetic field. The magnetic field onset of the zero-bias peak can be tuned by gates underneath the superconductor, which may result from the changing of chemical potential.