School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan, 44919, Korea.
Center for Electronic Materials, Korea Institute of Science and Technology , Seoul 02792, Korea.
Nano Lett. 2017 Jan 11;17(1):36-43. doi: 10.1021/acs.nanolett.6b03050. Epub 2016 Dec 9.
A two-dimensional electron gas emerged at a LaAlO/SrTiO interface is an ideal system for "spin-orbitronics" as the structure itself strongly couple the spin and orbital degree of freedom through the Rashba spin-orbit interaction. One of core experiments toward this direction is the nonlocal spin transport measurement, which has remained elusive due to the low spin injection efficiency to this system. Here we bypass the problem by generating a spin current not through the spin injection from outside but instead through the inherent spin Hall effect and demonstrate the nonlocal spin transport. The analysis on the nonlocal spin voltage, confirmed by the signature of a Larmor spin precession and its length dependence, displays that both D'yakonov-Perel' and Elliott-Yafet mechanisms involve in the spin relaxation at low temperature. Our results show that the oxide heterointerface is highly efficient in spin-charge conversion with exceptionally strong spin Hall coefficient γ ∼ 0.15 ± 0.05 and could be an outstanding platform for the study of coupled charge and spin transport phenomena and their electronic applications.
在 LaAlO/SrTiO 界面上出现的二维电子气是“自旋轨道电子学”的理想体系，因为该结构通过 Rashba 自旋轨道相互作用强烈耦合了自旋和轨道自由度。朝这个方向的核心实验之一是进行非局域自旋输运测量，但由于自旋注入效率低，该实验一直难以实现。在这里，我们通过产生自旋电流而不是通过外部自旋注入来绕过这个问题，而是通过固有自旋霍尔效应来实现非局域自旋输运。通过洛伦兹自旋进动及其长度依赖性的特征对非局域自旋电压的分析表明，在低温下，D'yakonov-Perel' 和 Elliott-Yafet 机制都涉及到自旋弛豫。我们的结果表明，氧化物异质界面在自旋-电荷转换方面非常高效，具有异常强的自旋霍尔系数γ∼0.15±0.05，可能是研究耦合电荷和自旋输运现象及其电子应用的杰出平台。
