Ferromagnetic phase transition in zinc blende (Mn,Cr)S-layers grown by molecular beam epitaxy

We studied the magnetization of zinc blende Mn1-xCrxS films embedded between diamagnetic ZnSe layers grown by molecular beam epitaxy with chromium mole fractions x ≤ 0.7. These ternary semiconductors exhibit an increasing ferromagnetic contribution with increasing x caused by competing antiferromagnetic and ferromagnetic coupling. As a result, whereas MnS in the zinc blende phase is a pure antiferromagnet, it was found that with increasing x zinc blende Mn1-xCrxS became a ferromagnet. The ferromagnetic phase transition dominates in case of x greater than about 0.5. Hence, we conclude that metastable zinc blende CrS will be a ferromagnetic material with half-metallic character in contrast to the analogous stable NiAs-structure which exhibits an antiferromagnetic phase transition.