Transport and Spin Hall Properties of A15 Phase Ta₃Sb Thin Films

The topological band structures of A15 compounds have been predicted to induce large spin Hall conductance[1]. Here, we have synthesized polycrystalline thin films of the A15 phase Ta₃Sb by sputter deposition. The crystal structure and phase purity have been confirmed with X-ray diffraction. Rutherford Backscattering Spectrometry shows a Ta/Sb atomic ratio of 4:1, which is consistent with the known Ta-Sb phase diagram [2] and suggests possible site mixing of Ta and Sb. The electrical resistivity of Ta₃Sb thin films increases with decreasing temperature above ~300K, and increases very weakly with further decrease in temperature until the superconducting transition at 0.887K. The dominant charge carriers in the normal state are hole type and their density decreases with decreasing temperature. From the harmonic Hall response of a Ta₃Sb/permalloy bilayer structure, the spin-orbit torque efficiency and the spin Hall conductivity of thin film Ta₃Sb are estimated to be 0.7 and 7325(hbar/2e) (Ω^-1cm^-1), respectively. [1] E. Derunova, Y. Sun, C. Felser, S.S.P. Parkin, B. Yan, and M.N. Ali, Science Advances 5, eaav8575 (2019). [2] F. Failamani, P. Broz, D. Macciò, S. Puchegger, H. Müller, L. Salamakha, H. Michor, A. Grytsiv, A. Saccone, E. Bauer, G. Giester, and P. Rogl, Intermetallics 65, 94 (2015).