# Artificial control of the bias-voltage dependence of tunnelling anisotropic magnetoresistance using quantization in a single-crystal ferromagnet

## TL;DR

This paper demonstrates how quantum size effects in a single-crystal ferromagnet can be used to control magnetic anisotropy dependence on bias voltage, advancing low-power spintronic memory technology.

## Contribution

It introduces a novel method to manipulate magnetic anisotropy via quantum size effects in GaMnAs, enabling voltage-controlled magnetic properties.

## Key findings

- Quantum size effect alters magnetic anisotropy symmetry from two-fold to four-fold.
- Gate-electric field enhances control over magnetic anisotropy.
- Potential for ultra-low-power magnetization manipulation in spintronics.

## Abstract

A major issue in the development of spintronic memory devices is the reduction of the power consumption for the magnetization reversal. For this purpose, the artificial control of the magnetic anisotropy of ferromagnetic materials is of great importance. Here, we demonstrate the control of the carrier-energy dependence of the magnetic anisotropy of the density of states (DOS) using the quantum size effect in a single-crystal ferromagnetic material, GaMnAs. We show that the mainly two-fold symmetry of the magnetic anisotropy of DOS, which is attributed to the impurity band, is changed to a four-fold symmetry by enhancing the quantum size effect in the valence band of the GaMnAs quantum wells. By combination with the gate-electric field control technique, our concept of the usage of the quantum size effect for the control of the magnetism will pave the way for the ultra-low-power manipulation of magnetization in future spintronic devices.