Ion-beam modification of the magnetic properties of GaMnAs epilayers

TL;DR

This study investigates how ion-beam irradiation can precisely modify the magnetic and transport properties of GaMnAs epilayers, revealing the formation of magnetic clusters and insulating states at high irradiation doses.

Contribution

It provides a systematic analysis of how ion-beam parameters affect magnetic and transport properties, including the formation of magnetic clusters and insulating states in GaMnAs.

Findings

Magnetic and transport properties can be controlled by ion-beam parameters.

High irradiation doses lead to magnetic clustering and insulating behavior.

Experimental results align with mean-field theoretical calculations.

Abstract

We study the controlled introduction of defects in GaMnAs by irradiating the samples with energetic ion beams, which modify the magnetic properties of the DMS. Our study focuses on the low-carrier-density regime, starting with as-grown GaMnAs films and decreasing even further the number of carriers, through a sequence of irradiation doses. We did a systematic study of magnetization as a function of temperature and of the irradiation ion dose. We also performed in-situ room temperature resistivity measurements as a function of the ion dose. We observe that both magnetic and transport properties of the samples can be experimentally manipulated by controlling the ion-beam parameters. For highly irradiated samples, the magnetic measurements indicate the formation of magnetic clusters together with a transition to an insulating state. The experimental data are compared with mean-field calculations for magnetization. The independent control of disorder and carrier density in the calculations allows further insight on the individual role of this two factors in the ion-beam-induced modification of GaMnAs.