Quantum Oscillations of Tunnel Magnetoresistance Induced by Spin-Wave Excitations in Ferromagnet-Ferromagnet-Ferromagnet Double Barrier Tunnel Junctions

TL;DR

This paper investigates quantum oscillations in tunnel conductance and magnetoresistance caused by spin-wave excitations in a ferromagnet-based double barrier junction, using a self-consistent Green function approach.

Contribution

It demonstrates that spin-wave excitations induce oscillations in conductance and TMR, aligning with recent experimental observations, and analyzes effects of magnon modes and electronic energy levels.

Findings

Conductance and TMR oscillate with bias voltage due to spin-wave excitations.

Oscillations are influenced by magnon modes and electronic energy levels.

Results agree with recent experimental observations.

Abstract

The possibility of quantum oscillations of the tunnel conductance and magnetoresistance induced by spin-wave excitations in a ferromagnet-ferromagnet-ferromagnet double barrier tunnel junction, when the magnetizations of the two side ferromagnets are aligned antiparallel to that of the middle ferromagnet, is investigated in a self-consistent manner by means of Keldysh nonequilibrium Green function method. It has been found that owing to the s-d exchange interactions between conduction electrons and the spin density induced by spin accumulation in the middle ferromagnet, the differential conductance and the TMR indeed oscillate with the increase of bias voltage, being consistent with the phenomenon that is observed recently in experiments. The effects of magnon modes, the energy levels of electrons as well as the molecular field in the central ferromagnet on the oscillatory transport property of the system are also discussed.