Effect of Cr-doping on structural and magnetic properties of BeTe

We report the growth of Cr-doped BeTe on GaAs(001) substrate under Te-rich condition by molecular beam epitaxy (MBE). The effects of Cr-doping on the structural and magnetic properties were investigated. Ferromagnetic behavior was observed for growth at substrate temperature of 250 degrees C with nominal Cr concentration of x > 13.0%. The Curie temperatures, T-c, for x similar to 13.0% and x similar to 17.0% were both similar to 170 K and the R-HEED pattern exhibiting (1 x 1) spotty patterns. On the other hand, for x similar to 27.0%, the T-c obtained was about similar to 250 K and hexagonal RHEED pattern was observed. The surface becomes less homogeneous with increasing x. This suggests that Cr atoms are unable to be incorporated substitutionally into the host lattices. We attribute the observation of ferromagnetic behavior to the formation of secondary phases. (c) 2005 Elsevier B.V. All rights reserved.