Magnetic Coupling in Ferromagnetic Semiconductor GaMnAs/AlGaMnAs Bilayer Devices

TL;DR

This study investigates the magnetic coupling in GaMnAs/AlGaMnAs bilayer devices, revealing how annealing alters magnetic orientation, coupling strength, and penetration depth, impacting magnetoresistance properties.

Contribution

It provides new insights into how annealing modifies magnetic coupling and anisotropy in ferromagnetic semiconductor bilayers, which was not previously well understood.

Findings

Magnetic interaction affects magnetoresistance in GaMnAs layers.

Annealing switches AlGaMnAs easy axis from out-of-plane to in-plane.

Annealed devices show doubled magnetic coupling penetration depth.

Abstract

We carefully investigated the ferromagnetic coupling in the as-grown and annealed ferromagnetic semiconductor GaMnAs/AlGaMnAs bilayer devices. We observed that the magnetic interaction between the two layers strongly affects the magnetoresistance of the GaMnAs layer with applying out of plane magnetic field. After low temperature annealing, the magnetic easy axis of the AlGaMnAs layer switches from out of plane into in-plane and the interlayer coupling efficiency is reduced from up to 0.6 to less than 0.4. However, the magnetic coupling penetration depth for the annealed device is twice that of the as-grown bilayer device.