Liu Mingrui, Hong Yanpeng, Xue Hongxia, Meng Jianchao, Jiang Weimin, Zhang Zhe, Ling Jingzhuo, Dou Ruifen, Xiong Changmin, He Lin, Nie Jiacai
Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China.
J Phys Condens Matter. 2020 May 27;32(23):235003. doi: 10.1088/1361-648X/ab7579.
Electrical transport property is closely related to the dimensionality of carriers' distribution. In this work, we succeed in tuning the carriers' distribution and the Rashba spin-orbit coupling at LaAlO/SrTiO interface by varying the oxygen pressure (c-P ) adopted in crystalline LaAlO growth. Measurements of the in-plane anisotropic magnetoresistance and the conducting-layer thickness indicate that the carriers' distribution changes from three to two dimensions with c-P increasing, i.e. the electron confinement gets stronger. Importantly, by measuring the low-temperature out-of-plane magnetoresistance and analyzing the weak localization/weak anti-localization, we find that the strength of Rashba spin-orbit coupling can be enhanced by electron confinement. The electron confinement is a manifestation of breaking of spatial inversion symmetry. Therefore, our work reveals the intimate relationship between spatial inversion symmetry breaking and Rashba spin-orbit coupling at the LaAlO/SrTiO interface, and provides a new method to tune the Rashba spin-orbit coupling, which is valuable in the application of oxide-spintronics.
电输运性质与载流子分布的维度密切相关。在本工作中，我们通过改变晶体LaAlO生长过程中采用的氧压（c-P），成功地调控了LaAlO/SrTiO界面处的载流子分布和Rashba自旋轨道耦合。面内各向异性磁电阻和导电层厚度的测量结果表明，随着c-P的增加，载流子分布从三维变为二维，即电子限域作用增强。重要的是，通过测量低温下的面外磁电阻并分析弱局域化/弱反局域化现象，我们发现电子限域作用可增强Rashba自旋轨道耦合的强度。电子限域作用是空间反演对称性破缺的一种表现。因此，我们的工作揭示了LaAlO/SrTiO界面处空间反演对称性破缺与Rashba自旋轨道耦合之间的紧密关系，并提供了一种调控Rashba自旋轨道耦合的新方法，这在氧化物自旋电子学应用中具有重要价值。
