Soft Superconducting Gap in Semiconductor Majorana Nanowires

Understand

We theoretically consider the ubiquitous soft gap measured in the tunneling conductance of semiconductor-superconductor hybrid structures, in which recently observed signatures of elusive Majorana bound states have created much excitement.

• We systematically study the effects of magnetic and non-magnetic disorder, temperature, dissipative Cooper pair breaking, and interface inhomogeneity, which could lead to a soft gap.
• We find that interface inhomogeneity with moderate dissipation is the only viable mechanism that is consistent with the experimental observations.
• Our work indicates that improving the quality of the superconductor-semiconductor interface should result in a harder induced gap.