We discuss the annealing-dependence of exchange bias in Ga1-xMnxAs epilayers that are overgrown with Mn. Although pure Mn is a known antiferromagnet, we find that the asgrown Mn overlayer does not produce any exchange coupling with Ga1-xMnxAs. Rather, our studies indicate that annealing in air is essential for creating the standard signatures of exchange bias (a clear shift in the magnetization hysteresis loop and an increased coercive field). We use X-ray photoelectron spectroscopy to characterize the compositional depth profile of both as-grown and rapid thermal annealed samples. These studies demonstrate that the cleanest exchange bias arises when the Mn overlayer is completely converted into MnO.
- Exchange bias;
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Physics and Astronomy (miscellaneous)