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 Co ₂MnSi 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 spinpolarization of charge carriers is also temperature independent.