Growth of ferromagnetic semiconductor Ge1−xMnxTe films on BaF2 (111) by ionized cluster beam deposition

Abstract

IV-VI ferromagnetic semiconductor Ge1−xMnxTe (x≈0.4) films were grown on BaF2 (111) substrates by an ionized cluster beam method. In neutral cluster beam deposition, Ge0.64Mn0.36Te films grown at substrate temperatures in the range from 250to300°C show an epitaxial relationship Ge0.64Mn0.36Te∕GeTe(111)‖BaF2(111). The crystallinity of the Ge0.64Mn0.36Te layer is improved with increasing substrate temperature. Further improvements of the crystal properties such as the crystallinity and the surface smoothness are accomplished by the proper acceleration of the ionized GeTe cluster, although the acceleration of the ionized MnTe cluster hardly gives rise to any noticeable improvement of the crystalline quality. The crystalline quality significantly affects the ferromagnetism: the enhancement of the spontaneous magnetization and the decrease of the coercive field are observed for the film grown using the ionized GeTe cluster at the acceleration voltage of 1kV due to the decreases of magnetic disorder caused by inhomogeneities in Mn distribution and pinning sites of domain-wall motion.