Efficient spin transport across a disordered interface in a low damping magnetic insulator/heavy metal bilayer

We demonstrate efficient spin transfer across a disordered interfacial layer that forms in low damping ferrimagnetic insulator lithium aluminum ferrite (LAFO) and tantalum bilayers. Despite the interfacial disorder, confirmed by transmission electron microscopy, we find a room temperature interfacial spin mixing conductance on the order of 10 14 Ω − 1 m − 2 similar to other LAFO-based bilayers with epitaxial interfaces. Broadband ferromagnetic resonance measurements confirm a linewidth broadening in LAFO following the addition of a Ta layer, consistent with the effects of spin pumping. Furthermore, the presence of spin current generated in the Ta layer by spin pumping is confirmed with inverse spin Hall effect measurements. Measurements of the Ta thickness dependence of the spin Hall magnetoresistance and the Gilbert damping enhancement indicate that the Ta spin diffusion length is on the order of 1nm. This work not only provides a surprising example of efficient spin transport across a disordered interface but also demonstrates the potential for low damping spinel ferrites as a robust system for efficient spin wave spintronics.