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 °C with nominal Cr concentration of x > 13.0%. The Curie temperatures, Tc, for x ∼ 13.0% and x ∼ 17.0% were both ∼ 170 K and the RHEED pattern exhibiting (1 × 1) spotty patterns. On the other hand, for x ∼ 27.0%, the Tc obtained was about ∼ 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.