Quantitative determination of [0 1 0] uniaxial anisotropy and the pinning energy in (Ga,Mn)As films

Abstract

A number of recent magnetization and transport studies show a rich spectrum of magnetic anisotropies of prototypical diluted magnetic semiconductors (Ga,Mn)As. However, few investigations thus far have provided the quantitative determination of [0 1 0] uniaxial magnetic anisotropy (UMA) and the domain-wall pinning field, which are commonly overshadowed by strong cubic anisotropy and huge Zeeman energy. Here we combine results of planar Hall effect experiments carried out at low magnetic fields, and calculations via a modifying Stoner–Wohlfarth model to address this issue. The results of this work indicate that the strength of [0 1 0] UMA constant can be unexpectedly large, even twice as large as that of [] UMA, which differs drastically from the often accepted view that the former is only one tenth of the latter in magnitude. We also obtain quantitative values of the pinning field, which is not constant as expected. Instead, it decreases with increasing temperature or external field. These findings would fulfil the complete picture on magnetic anisotropies of (Ga,Mn)As.