Thin film dilute ferromagnetic semiconductors Sb 2 − x Cr x Te 3 with a Curie temperature up to 190 K

Thin film semiconductors ${\mathrm{Sb}}_{2\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{Te}}_{3}$ $(0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.59)$ based on tetradymite-type structure of ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$ have been prepared on the (0001) sapphire substrates by low-temperature molecular beam epitaxy. The films display ferromagnetism with the Curie temperature increasing nearly linearly with the content of Cr incorporated in the lattice. The highest Curie temperature reached so far is $190\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in a ${\mathrm{Sb}}_{1.41}{\mathrm{Cr}}_{0.59}{\mathrm{Te}}_{3}$ film. Structural studies, magnetic characterization, and transport measurements indicate the robust nature of the magnetic state that has its easy axis of magnetization perpendicular to the plane of the film. The structures thus represent diluted magnetic semiconductors with a high Curie temperature and highly anisotropic properties.