Anomalous Hall Effect of Co2MnSi thin films on GaAs (001)

The Heusler alloy Co$_{2}$MnSi is a leading candidate material for spin injection and detection in hybrid spintronic devices. Recent measurements of $\sim $60{\%} transport spin polarization by point contact Andreev reflection\footnote{ L. J. Singh \textit{et al}, APL \textbf{84,} 2367-2369 (2004).} and tunneling magnetoresistance\footnote{ J. Schmalhorst \textit{et al}, PRB \textbf{70,} art. no.-024426 (2004).} have demonstrated that below 10K Co$_{2}$MnSi significantly outperforms the elemental ferromagnets and other high Curie temperature ferromagnets such as NiMnSb. Here we study the anomalous Hall effect in a series of highly textured Co$_{2}$MnSi thin films on lattice-matched GaAs, and contrast with the corresponding measurements of polycrystalline NiMnSb films on silicon. The anomalous Hall effect is a function of the transport spin polarization. The implications of the normal and anomalous Hall signals as a function of temperature and film thickness will be discussed.