Quantum theory of tunneling magnetoresistance in GaMnAs/GaAs/GaMnAs heterostructures

TL;DR

This paper presents a quantum theoretical analysis of tunneling magnetoresistance in GaMnAs/GaAs/GaMnAs heterostructures, revealing how TMR depends on barrier thickness, temperature, and voltage, and aligning well with experimental data.

Contribution

It introduces a quantum model incorporating spin-splitting effects to explain TMR behavior in magnetic semiconductor heterostructures, matching recent experimental findings.

Findings

TMR ratios over 65% at zero temperature with thin barriers

TMR decreases rapidly with increasing barrier thickness and voltage

High voltage and low thickness cause TMR to first increase then decrease

Abstract

Using a quantum theory including spin-splitting effect in diluted magnetic semiconductors, we study the dependence of tunneling magnetoresistance (TMR) on barrier thickness, temperature and applied voltage in GaMnAs/GaAs/GaMnAs heterostructures. TMR ratios more than 65% are obtained at zero temperature, when one GaAs monolayer ($\approx$ 0.565 nm) is used as a tunnel barrier. It is also shown that the TMR ratio decreases rapidly with increasing the barrier thickness and applied voltage, however at high voltages and low thicknesses, the TMR first increases and then decreases. Our model calculations well explain the main features of the recent experimental observations.