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The spin Hall effect (SHE) [1] allows for a reciprocal conversion between charge and spin currents using the spin orbit coupling which can be at the core of several promising spintronics devices. The spin orbit interaction is used to produce a transverse flow of spin or charge in response to a longitudinal excitation, these are the direct or inverse SHE. The spin Hall angle (SHA), the ratio of longitudinal and transverse electronic conductivities, is the characterising parameter of this conversion. So far, large SHA have been reported in transition metals like Pt, Pd, W, Beta-Ta and in a few alloys with large spin orbit coupling impurities: CuIr, CuBi or CuPb [2].
In this presentation we will report on our study of the SHA in Au based alloys [3] which exhibits a non-monotonic relation with the impurity concentration. In the regime of diluted alloys this behaviour suggests the dominent side-jump contribution to the spin Hall resistivity, thus allowing precise tuning of the SHA as a function of impurities concentration. We will present our analyses results by using the Lateral Spin Valves, with newly introduced spin-absorption model adapted to the case of the strong spin-orbit interactions and by using complementary Ferromagnetic-Resonance/Spin-Pumping technique thus demonstrating very large SHA of the order of 15 % or even larger.
[1] J.E. Hirsch, PRL 83, 1834 (1999).
[2] Y. Niimi et al., PRL 106, 126601 (2011), PRL 109, 156602 (2012), PRB 89, 054401 (2014).
[3] P. Laczkowski et al., APL 104, 142403 (2014)
[4] E. Saitoh, et al., APL 88, 182509 (2006).
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