Effects of capping on the Ga1−xMnxAs magnetic depth profile

Annealing can increase the Curie temperature and net magnetization in uncapped Ga1−xMnxAs films, effects that are suppressed when the films are capped with GaAs. Previous polarized neutron reflectometry (PNR) studies of uncapped Ga1−xMnxAs revealed a pronounced magnetization gradient that was reduced after annealing. We have extended this study to Ga1−xMnxAs 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.

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