Negative differential conductance and magnetoresistance oscillations due to spin accumulation in ferromagnetic double-island devices

TL;DR

This paper theoretically investigates how spin accumulation and charging effects in ferromagnetic double-island devices cause periodic oscillations in differential conductance and magnetoresistance, depending on bias voltage and spin relaxation time.

Contribution

It introduces a theoretical analysis of spin-dependent transport showing how spin accumulation leads to oscillations in conductance and magnetoresistance in double-island devices.

Findings

Periodic modulation of differential conductance observed.

Oscillations in tunnel magnetoresistance with bias voltage.

Long spin relaxation times enhance oscillation effects.

Abstract

Spin-dependent electronic transport in magnetic double-island devices is considered theoretically in the sequential tunneling regime. Electric current and tunnel magnetoresistance are analyzed as a function of the bias voltage and spin relaxation time in the islands. It is shown that the interplay of spin accumulation on the islands and charging effects leads to periodic modification of the differential conductance and tunnel magnetoresistance. For a sufficiently long spin relaxation time, the modulations are associated with periodic oscillations of the sign of both the tunnel magnetoresistance and differential conductance.