Antisite effect on ferromagnetism in (Ga,Mn)As

TL;DR

This study investigates how arsenic antisite defects affect the magnetic and electronic properties of (Ga,Mn)As, revealing that controlling antisite concentration is crucial for optimizing ferromagnetism at low doping levels.

Contribution

It provides a systematic analysis of As-antisite effects on Curie temperature and hole density in (Ga,Mn)As, highlighting the importance of stoichiometry control.

Findings

As-antisites limit Curie temperature and can suppress ferromagnetism at low doping.

Deviations from the expected Tc ~ p^0.33 relationship are observed below 1.5% Mn.

Controlling As-antisite concentration is essential for tuning magnetic properties in (Ga,Mn)As.

Abstract

We study the Curie temperature and hole density of (Ga,Mn)As while systematically varying the As-antisite density. Hole compensation by As-antisites limits the Curie temperature and can completely quench long-range ferromagnetic order in the low doping regime of 1-2% Mn. Samples are grown by molecular beam epitaxy without substrate rotation in order to smoothly vary the As to Ga flux ratio across a single wafer. This technique allows for a systematic study of the effect of As stoichiometry on the structural, electronic, and magnetic properties of (Ga,Mn)As. For concentrations less than 1.5% Mn, a strong deviation from Tc ~ p^0.33 is observed. Our results emphasize that proper control of As-antisite compensation is critical for controlling the Curie temperatures in (Ga,Mn)As at the low doping limit.