Structure, magnetic and optical properties, and Hall effect of Co- and Fe-doped SnO2 films

Magnetically doped ${\text{SnO}}_{2}$ is a promising dilute magnetic semiconductor and may also be applicable in a variety of magneto-optical applications. Epitaxial films of ${\text{Sn}}_{1\ensuremath{-}x}{\text{Co}}_{x}{\text{O}}_{2}$ $(x\ensuremath{\le}0.2)$ and ${\text{Sn}}_{1\ensuremath{-}x}{\text{Fe}}_{x}{\text{O}}_{2}$ $(x\ensuremath{\le}0.4)$ were grown by pulsed-laser deposition on $R$-plane ${\text{Al}}_{2}{\text{O}}_{3}$ substrates. Structural, magnetic, and magnetotransport measurements consistently point to a source of magnetism within the host lattice rather than from an impurity phase. The films are strained and their magnetic anisotropy is consistent with the presence of substantial amounts of magnetoelastic high-spin ${\text{Fe}}^{2+}$, or high- or low-spin ${\text{Co}}^{2+}$. ${\text{Sn}}_{0.9}{\text{Co}}_{0.1}{\text{O}}_{2}$ films have a reasonably high Faraday rotation of 570\ifmmode^\circ\else\textdegree\fi{}/cm, and the refractive index $n$ and extinction coefficient $k$ at 1550 nm wavelength are 1.957 and 0.0102, respectively.