Anomalous Nernst effect in Co₂MnSi thin films

Separation of the anomalous Nernst and spin Seebeck voltages in bilayer devices is often problematic when both layers are metallic, and the anomalous Nernst effect (ANE) becomes non-negligible. Co₂MnSi, a strong candidate for the spin generator in spin Seebeck devices, is a predicted half-metal with 100% spin polarisation at the Fermi energy, however, typically B2 or L2₁ order is needed to achieve this. We demonstrate the optimisation of thin film growth of Co₂MnSi on glass, where choice of deposition and annealing temperature can promote various ordered states. The contribution from the ANE is then investigated to inform future measurements of the spin Seebeck. A maximum ANE coefficient of 0.662 µV K⁻¹ is found for an A2 disordered polycrystalline Co₂MnSi film. This value is comparable to ordered Heusler thin films deposited onto single crystal substrates but obtained at a far lower fabrication temperature and material cost. (paper)