High Temperature Ferromagnetism with a Giant Magnetic Moment in Transparent Co-doped S n O 2 − δ

The occurrence of room temperature ferromagnetism is demonstrated in pulsed laser deposited thin films of ${\mathrm{S}\mathrm{n}}_{1\ensuremath{-}x}{\mathrm{C}\mathrm{o}}_{x}{\mathrm{O}}_{2\ensuremath{-}\ensuremath{\delta}}$ ($x<0.3$). Interestingly, films of ${\mathrm{S}\mathrm{n}}_{0.95}{\mathrm{C}\mathrm{o}}_{0.05}{\mathrm{O}}_{2\ensuremath{-}\ensuremath{\delta}}$ grown on $R$-plane sapphire not only exhibit ferromagnetism with a Curie temperature close to 650 K, but also a giant magnetic moment of $7.5\ifmmode\pm\else\textpm\fi{}0.5{\ensuremath{\mu}}_{B}/\mathrm{C}\mathrm{o}$, not yet reported in any diluted magnetic semiconductor system. The films are semiconducting and optically highly transparent.