Negative Tunneling Magneto-Resistance in Quantum Wires with Strong Spin-Orbit Coupling

TL;DR

This paper investigates how strong spin-orbit coupling in quantum wires causes anisotropic and sign-changing tunneling magneto-resistance, explaining recent experimental observations at oxide interfaces.

Contribution

It introduces a model of a magnetic tunnel junction with a quantum wire featuring magnetic order and Rashba SOC, revealing novel TMR behavior.

Findings

TMR exhibits strong anisotropy and sign reversal depending on polarization direction.

The interplay of one-dimensionality, magnetic order, and SOC explains observed phenomena.

Results suggest new ways to control spin transport in quantum wire devices.

Abstract

We consider a two-dimensional magnetic tunnel junction of the FM/I/QW(FM+SO)/I/N structure, where FM, I and QW(FM+SO) stand for a ferromagnet, an insulator and a quantum wire (QW) with both magnetic ordering and Rashba spin-orbit (SOC), respectively. The tunneling magneto-resistance (TMR) exhibits strong anisotropy and switches sign as the polarization direction varies relative to the QW axis, due to interplay among the one-dimensionality, the magnetic ordering, and the strong SOC of the QW. The results may provide a possible explanation for the sign-switching anisotropic TMR recently observed in the LaAlO$_3$/SrTiO$_3$ interface.