Topological Superconductivity in Ferromagnetic Insulator-Superconductor-Semiconductor Heterostructures

Superconductor-semiconductor heterostructures in magnetic field are widely viewed as a promising platform for realizing topological superconductivity. In this work, using Usadel equation we theoretically investigate ferromagnetic insulator-superconductor-semiconductor heterostructures taking into account spin-orbit scattering, spin-flip scattering and Zeeman field in the parent superconductor. We find that critical field needed to induce topological superconductivity can be reduced by the presence of Zeeman field in the parent superconductor while preserving value of the topological gap. Besides, we find that spin-orbit scattering, if present in the parent superconductor, can substantially increase critical Zeeman field of the parent superconductor, thus potentially allowing for observation of topological phase at higher fields. Our results could be of use for understanding recent and future experiments with EuS-Al-InAs heterostructures [1].

[1] Vaitiekenas, S., Liu, Y., Krogstrup, P. et al. Zero-bias peaks at zero magnetic field in ferromagnetic hybrid nanowires. Nat. Phys. (2020)