Nanoscale Ge1−xMnxTe ferromagnetic semiconductors
This article discusses the structure characterizations, magnetic and transport behaviors of the nanoscale ferromagnetic semiconductors Ge1-xMnxTe grown by molecular beam epitaxy with various manganese compositions x ranging from 0.14 to 0.98. After providing an overview of the growth procedure and characterization, the article analyzes the structures of the Ge1-xMnxTe system using X-ray diffraction and high-resolution transmission electron microscopy. It then considers the optical, magnetic and transport properties of the semiconductors and shows that the crystal quality is degraded and the proportion of amorphous phase increases with increasing Mn composition. Nanoclusters and nanoscale grains can be observed when x > 0.24, which greatly affect their magnetic and electronic properties. The magnetic anisotropy is weakened due to different orientations of the clusters embedded in the GeTe host. An anomalous Hall effect is also observed in the samples, which can be attributed to extrinsic skew scattering.