Spin transport in ferromagnet-InSb nanowire quantum devices

Topological excitations such as Majorana fermions provide unique pathways to fault-tolerant quantum computing. Recent progress has been enabled by proximity effects between non-superconducting materials and superconductors. Currently, Majorana devices based on semiconductors require application of an external magnetic field to open a helical gap. However, the presence of magnetic field can suppress the superconductivity and place geometric restrictions on the device. A promising path forward is to realize Majorana modes without field by integrating ferromagnets or antiferromagnets with semiconductors and superconductors. Here, we study ballistic InSb nanowire (NW) devices with ferromagnetic contacts. Magneto-transport measurements on these devices display hysteretic features spanning from the many-modes regime to few modes, which demonstrate spin-splitting transport across the NWs. Moreover, electrostatic gating can tune the transport in a regime where the device acts as a spin filter.