Spin-orbit coupling induced non-local signal in quasi 2DEG of LAO/STO

Oxide hetero interface have received growing attention due to unique electronic behaviors, such as coexistence of superconductivity and ferromagnetism, strong Rashba-type spin-orbit coupling, etc. Here, we studied non-local spin signal of gate-controlled Rashba field in quasi-2DEG of LaAlO3/SrTiO3 (LAO/STO) interface. We fabricated simple hall-bar (H-bar) like geometry to measure non-local signal depends on different channel lengths (2~10um). Cleaned 5mm x 5mm size of LAO/STO sample was patterned using e-beam lithography & Reactive ion etching process. Fabricated sample was putted in a Physical Property Measurement System. And all electrical measurement was performed in a vacuum condition using Keithely source meter (K2636) and nanovoltameter (K2182). When an electric current flows one of the lines of the H-bar structures, a transverse spin current due to the spin orbit coupling is induced in the connecting part. Consequently, this spin current produces a non-local voltage difference in the opposite line of the H-bar structures via inverse spin hall effect. The non-local signals were studied under different angle of magnetic field and variation of applied gate voltage. This work was supported by a grant from (Future Challenge Project or Creativity and Innovation Project) funded by the Ulsan National Institute of Science and Technology and Basic Science Research Program through the National Research Foundation of Korea (No. 2011-0014651

Gate dependent non-local spin resistance in an Au-patched graphene

Enhanced spin-orbit coupling in grapheme can induce spin Hall effect, which can be adapted to electrically generate or detect a spin current in the spin logic device without a ferromagnet. Recently, spin Hall effect in decorated graphenes has been experimentally observed by non-local transport studies. However, results on the non-local measurements in graphene hall bar devices exploiting spin Hall effect have been under controversy. In this study, we introduced an ultra-thin Au-patch on a graphene surface to enhance the spin-orbit coupling, and employed an H-bar type device to probe the nonlocal spin signal induced by spin Hall effect. The geometry of the studied H-bar devices has channels of 1 ??m width and 5.6 ??m length. An ultra-thin Au patch (\textasciitilde 1 nm) was deposited by a thermal evaporation. And in-plane field dependent spin precession signature can be observed at particular gate voltage. At that point, the spin hall angle and the spin relaxation length of the Au-patch graphene device were ?? \textasciitilde 8.8 {\%} and ??s \textasciitilde 2.2 ??m at 2 K, respectively. The estimated spin relaxation rates were proportional to square of temperature, suggesting an Elliott-Yafet spin relaxation mechanism

Spin Hall Effect Driven Non-Local Spin Diffusion at Oxide Heterointerfaces

The conductive interface at LaAlO3/SrTiO3 (LAO/STO) can be designed to exhibit high mobility with tunable carrier concentration and exhibits various unique electronic behaviors. 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. 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 spin-charge conversion with exceptionally strong spin Hall coefficient ?? \textasciitilde 0.24 and could be an outstanding platform for the study of coupled charge and spin transport phenomena and their electronic applications