Effects of Capping on the (Ga,Mn)As Magnetic Depth Profile

TL;DR

This study investigates how GaAs capping affects the magnetic properties and impurity redistribution in (Ga,Mn)As films during annealing, showing that capping inhibits improvements seen in uncapped films.

Contribution

It provides new insights into the role of GaAs capping in suppressing annealing-induced magnetic enhancements in (Ga,Mn)As.

Findings

Annealing does not increase Curie temperature or magnetization in capped films.

Capped films retain a magnetization gradient after annealing.

GaAs cap inhibits Mn impurity redistribution during annealing.

Abstract

Annealing can increase the Curie temperature and net magnetization in uncapped (Ga,Mn)As films, effects that are suppressed when the films are capped with GaAs. Previous polarized neutron reflectometry (PNR) studies of uncapped (Ga,Mn)As revealed a pronounced magnetization gradient that was reduced after annealing. We have extended this study to (Ga,Mn)As capped with GaAs. We observe no increase in Curie temperature or net magnetization upon annealing. Furthermore, PNR measurements indicate that annealing produces minimal differences in the depth-dependent magnetization, as both as-grown and annealed films feature a significant magnetization gradient. These results suggest that the GaAs cap inhibits redistribution of interstitial Mn impurities during annealing.