Efficient spin to charge conversion and spin memory loss mitigation in oriented RuO₂ films

RuO₂, a transition metal oxide, is attracting attention in spintronics for its unique altermagnetic properties, which influence spin currents. Its ability to produce large spin-orbit torques and spin Hall effects is key for energy-efficient magnetic memory and logic devices. Additionally, the tunable thickness and crystallinity of RuO₂ thin films optimize torque efficiency for low-power switching. Spin pumping, a versatile method for investigating spin dynamics in RuO₂ thin films, has garnered considerable interest because of its straightforward, non-invasive and uncomplicated approach to addressing impedance mismatch and direct measurement of spintronic parameters. Here we present a systematic and detailed analysis on the efficient spin to charge conversion in (110)-oriented RuO₂ films with amorphous CoFeB as spin source. The spin Hall angle, and spin diffusion length were estimated to be 0.14 ± 0.01 and 4.58 ± 0.40 nm, respectively. The spin Hall conductivity of 998.89 ± 58.23 · Ω⁻¹ \, cm⁻¹e has been estimated which is theoretically predicted to be of the similar order. The interfacial spin transparency has been achieved to be 90%. We have shown that the spin memory loss at the RuO₂/CoFeB interface is 15%, which is very small.