Temperature insensitivity of the spin-polarization in Co2MnSi films on GaAs (001)

The Heusler alloys Co2MnSi and NiMnSb are predicted to be 100% spin-polarized and are leading candidate materials for spin-injection and detection in hybrid spintronic devices. Co2MnSi is lattice matched with GaAs, whereas NiMnSb is strongly mismatched to GaAs. Here, we study the temperature and thickness dependence of the anomalous Hall (AH) effect in a series of textured, predominantly (001) oriented, sputter deposited Co2MnSi thin films on GaAs, and compare the behaviour to that of a molecular beam epitaxy (MBE) grown NiMnSb film on GaAs (001) with low antisite disorder. We show that the Co2MnSi films have temperature independent AH conductivity, even for the thinnest films with strongly temperature dependent saturation magnetization. We discuss whether a temperature insensitive AH conductivity necessarily indicates that the spin-polarization of charge carriers is also temperature independent.