Non-local Spin Diffusion Driven by Giant Spin Hall Effect at Oxide Heterointerfaces

Abstract

The conductive interface at LaAlO3/SrTiO3 (LAO/STO) can be designed to exhibit high mobility with tunable carrier concentration. And this interface exhibits various unique electronic behaviors, such as superconductibity, ferromagnetism, and coeistence of them. This interface could be also interesting playground for ‘'spin-orbitronics’' as the structure itself strongly couple the spin and orbital degree of freedom through the Rashba spin-orbit interaction. We report the non-local spin diffusion at LAO/STO interface induced by the spin Hall effect. The Hall-bar (H-bar) like geometry was employed to generate a transverse spin polarized current, which in turn can be detected by the inverse spin Hall effect. As confirmed by the signature of a Larmor spin precession and its length dependence, our results clearly demonstrated the non-local spin diffusion as well as effective spin charge conversion at this oxide heterointerface. The analysis on the non-local spin voltage displays that both D’'yakonov-Perel’' and Elliott-Yafet mechanisms involve in the spin relaxation. Our results show that the oxide heterointerface is highly efficient in spincharge conversion with exceptionally strong spin Hall coefficient γ ~ 0.24 and could be an outstanding platform for the study of coupled charge and spin transport phenomena and their electronic applications.