Properties of Bulk Antimonide-based Magnetic Semiconductors

By using the Bridgeman method, the growth of GaMnSb bulk materials and their structural, magnetic and electric characterizations are reported. Room-temperature ferromagnetic signals were observed at the Mn-rich regions, whereas the Mn-deficient areas exhibit diamagnetism. The saturated magnetization in the Mn-rich areas is merely 0.013μ_B per Mn atom, which is far lower than the theoretical value. Electric measurements show that these two regions almost have identical hole concentrations, which indicates that the difference in the magnetic behaviors is not correlated with the carrier concentration. The characterizations by energy-dispersive X-ray spectroscopy demonstrate that the distribution of Mn atoms is more uniform in the Mn-poor regions than that in the Mn-rich regions. Moreover, the X-ray diffraction measurements reveal the appearance of MnSb impurity phase in the Mn-rich regions. All these results show that the ferromagnetism observed here is extrinsic.