Novel Majorana mode and magnetoresistance in ferromagnetic superconducting topological insulator

Abstract

Among the potential applications of topological insulators, we investigate theoretically the effect of coexistence of proximity-induced ferromagnetism and superconductivity on the surface states of 3-dimensional topological insulator, where the superconducting electron-hole excitations can be significantly affected by the magnetization of ferromagnetic order. We find that, Majorana mode energy, as a verified feature of TI F/S structure, along the interface sensitively depends on the magnitude of magnetization $m_{zfs}$ in FS region, while its slope in perpendicular incidence presents steep and no change. Since the superconducting gap is renormalized by a factor $\eta(m_{zfs})$, hence Andreev reflection is more or less suppressed, and, in particular, resulting subgap tunneling conductance is more sensitive to the magnitude of magnetizations in FS and F regions. Furthermore, an interesting scenario happens at the antiparallel configuration of magnetizations $m_{zf}$ and $m_{zfs}$ resulting in magnetoresistance in N/F/FS junction, which can be controlled and decreased by tuning the magnetization magnitude in FS region.