Spin to charge current conversion by the inverse spin Hall effect in the metallic antiferromagnet Mn2Au at room temperature

Abstract

We report experiments demonstrating the spin to charge current conversion by means of the inverse spin Hall effect in ultrathin films of the metallic antiferromagnet $\mathrm{M}{\mathrm{n}}_{2}\mathrm{Au}$ at room temperature. The $\mathrm{M}{\mathrm{n}}_{2}\mathrm{Au}$ films, of different thicknesses, were grown by dc sputtering directly onto crystalline films of the ferrimagnetic insulator yttrium iron garnet (YIG). The spin currents are generated in the YIG film by two different processes, spin pumping effect (SPE) and spin Seebeck effect (SSE). In the SPE experiments we use microwave-driven ferromagnetic resonance of the YIG film to generate a spin current that is injected into the $\mathrm{M}{\mathrm{n}}_{2}\mathrm{Au}$, while in the SSE experiments the spin current is generated by a thermal gradient across the YIG film in the configuration of the longitudinal spin Seebeck effect. From these measurements, we obtain for $\mathrm{M}{\mathrm{n}}_{2}\mathrm{Au}$ at room temperature a spin-diffusion length, ${\ensuremath{\lambda}}_{S}$, of 1.6 nm and a spin Hall angle, ${\ensuremath{\theta}}_{\mathrm{SH}}\ensuremath{\approx}0.04$, which is comparable to the value for platinum.