Direct Observation of a Systematic Change of the Magnetic-Domain Structure With Temperature in 50-nm-MnAs/GaAs(001)

We present the results of a systematic change of magnetic-domain structure of epitaxial MnAs film on GaAs(001) in a temperature range of 17.5 $^\circ$C–45 $^\circ$C by magnetic-force microscopy (MFM). As temperature decreases, the small localized domains are formed and gradually collapse to the stripe domains. Finally, at 17.5 $^\circ$C the whole film turns to be a nearly single magnetic domain including only a small fraction of the nonferromagnetic $\beta$ -MnAs phase, as directly confirmed in the MFM experiment.