Tunneling Magnetoresistance in Junctions Composed of Ferromagnets and Time-Reversal Invariant Topological Superconductors

TL;DR

This paper demonstrates that junctions combining ferromagnets and time-reversal invariant topological superconductors can exhibit high tunneling magnetoresistance due to spin-dependent Andreev reflections, even with weak magnetization.

Contribution

It introduces a novel mechanism for high tunneling magnetoresistance in ferromagnet-topological superconductor junctions without requiring strong magnetization.

Findings

High tunneling magnetoresistance achievable with weak ferromagnets

Perfect spin-equal Andreev reflection occurs at specific spin alignments

Magnetoresistance persists even with featureless tunneling barriers

Abstract

Tunneling Magnetoresistance between two ferrromagnets is an issue of fundamental importance in spintronics. In this work, we show that tunneling magnetoresistance can also emerge in junctions composed of ferromagnets and time-reversal invariant topological superconductors without spin-rotation symmetry. Here the physical origin is that when the spin-polarization direction of injected electron from the ferromagnet lying in the same plane of the spin-polarization direction of Majorana zero modes, the electron will undergo a perfect spin-equal Andreev reflection, while injected electrons with other spin-polarization direction will be partially Andreev reflected and partially normal reflected, which consequently have a lower conductance, and therefore, the magnetoresistance effect emerges. Compared to conventional magnetic tunnel junctions, an unprecedented advantage of the junctions studied here is that arbitrary high tunneling magnetoresistance can be obtained even the magnetization of the ferromagnets are weak and the insulating tunneling barriers are featureless. Our findings provide a new fascinating mechanism to obtain high tunneling magnetoresistance.