Topological superconductivity in ferromagnetic hybrid nanowires

Hybrid nanowire devices combining expitaxial ferromagnetic insulator and superconducting layers have been recently proposed [1-3] as a platform for topological superconductivity without the need of applying an external magnetic field. In this theoretical work we show that the topological regime can arise in these devices provided that certain geometrical and electrostatic conditions are met. To this end we perform detailed microscopic simulations in which we take into account both the magnetic and superconducting proximity effects. We also include self-consistently the interaction with the electrostatic environment that typically surrounds these hybrid wires in the experiments. Our calculations indicate that there is a strong magnetization in the nanowire regions close to the interface with the ferromagnet and a weaker one inside the superconductor. As a consequence, the topological phase depends critically on the wavefunction location across the wire’s cross-section, something that can be properly controlled by tuning the external gates.

References:
[1] Y. Liu et al., ACS App. Mat. & Int. 12, 8780 (2020).
[2] Y. Liu et al., Nano Lett. 20, 456 (2020).
[3] S. Vaitiekenas et al., Nat. Phys. (2020).