Spin Seebeck coefficient enhancement by using Ta₅₀W₅₀ alloy and YIG/Ru interface

This paper reports that Ta₅₀W₅₀ alloy has a higher spin Hall angle than that of β-W by measuring the spin Seebeck coefficients for Fe₅Y₃O₁₂ (YIG)/Ru/Ta₅₀W₅₀ and YIG/Ru/W systems. The spin Seebeck coefficient increased by inserting Ru, and the YIG/Ru/Ta₅₀W₅₀ system achieved 2.4 times the magnitude of spin Seebeck coefficient of the conventional YIG/Pt system although Ru and Ta₅₀W₅₀ have spin Hall angles with opposite signs. Ru seems to recover the spin mixing conductance that is decreased by Ta–W oxidation at its interface with YIG. To enhance the spin Seebeck coefficient, materials having a high spin Hall angle can be combined with materials having a high spin mixing conductance. (paper)