Magnetic Properties of Ge$_{1-x}$Mn$_{x}$Te Thin Films

We have measured the magnetization of Ge$_{1-x}$Mn$_{x}$Te thin films with 0.08 $<$ x $<$ 0.19 at magnetic fields up to 7 T at temperatures from 2 to 385 K. The monocrystalline epitaxial layers of Ge$_{1-x}$Mn$_{x}$Te were grown on (111)-oriented BaF$_{2}$ crystalline substrates in a home-built MBE system. The layer structure was rhombohedral, thickness in the range 0.5 -- 1 micron, and hole carrier concentration of the order 10$^{21}$ cm$^{-3}$. Magnetization measurements were made using a Quantum Design MPMS system. At low temperatures the samples were ferromagnetic. The ferromagnetic -- paramagnetic transition was observed in various samples in a broad temperature range from 20 -- 100 K. In some samples we have seen two peaks in the temperature dependence of the low-field magnetization. These peaks may be evidence of two chemical phases or of an electronic phase separation. The origin of this effect is under investigation at the present time.