Magnetic Characterization of Molecular Beam Epitaxy Grown Cd1xMnxTe Structures

Abstract

Results of previous studies [1] on magnetic properties of CdMnTe epilayers grown by molecular beam epitaxy (MBE) on InSb substrates [2] revealed that magnetization measurements may serve as an effective tool for investigation of Mn distribution within the epilayer. Namely, we found systematically greater values of the high temperature magnetic susceptibility in MBE layers than in their bulk counterparts. Since spin—spin interactions in Cd 1-x Mn xTe are antiferromagnetic it was concluded in [1] that a smaller clusterization occurred during the non-equilibrium growth. However, this process did not lead to a change of magnetic properties at low temperatures, where transitions to either spin-glass (x < 0.60) or antiferromagnetic (x = 0.70) phases were observed to occur at the same temperatures as in bulk samples. The latter fact suggests that the growth technique does not affect these properties of the distribution function of magnetic atoms which is important for the long range magnetic order. Also, an enhanced paramagnetic contribution to the magnetic susceptibility at low temperatures has been found in CdTe/CdMnTe superlattice. The latter effect was assigned to the presence of isolated paramagnetic ions in the interface regions as a result of an intermixing of Mn and Cd ions and/or a smaller number of magnetic bonds at the interface. In this paper we report results of magnetic measurements performed on both thick (Cd0.60 Mn0.40Τe and MnTe) epilayer and CdTe/Cd 0.50Mn0.50Te superlattices grown by MBE on GaAs substrates [3]. In order to reduce effects of