Li Ming, Yang Ruishu, Wei Xiangyang, Yin Hang, Wang Shuanhu, Jin Kexin
Shaanxi Key Laboratory of Condensed Matter Structures and Properties and MOE Key Laboratory of Materials Physics and Chemistry under Extraordinary Conditions, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China.
ACS Appl Mater Interfaces. 2021 May 12;13(18):21964-21970. doi: 10.1021/acsami.1c02295. Epub 2021 Apr 29.
Complex oxide heterointerfaces provide a platform to manipulate spin-orbit coupling under the broken inversion symmetry. Moreover, their weak antilocalization (WAL) effect displays quantum coherent behavior due to the strong spin-orbit coupling. Herein, we break through the limitation of lattice mismatch at ReAlO/STO (Re = La, Pr, Nd, Sm, and Gd) heterointerfaces and obtain their two-dimensional electric gas (2DEG) by spin coating. The effect of different Re elements in the resulting quantum corrections on the conductivity is investigated. It is observed that the conductivity of heterointerfaces is reduced with larger atomic numbers due to the ionization potential of Re elements. Moreover, magnetoresistance (MR) measurements in a perpendicular or a parallel field distinctly uncover strong Rashba spin-orbit coupling (SOC) in ReAO/STO samples besides SAO/STO (Re = Sm) and GAO/STO (Re = Gd), and the effective fields of the SOC () gradually increase from LAO/STO (Re = La, = 0.82 T) to NAO/STO (Re = Nd, = 1.37 T) at 2 K. The competition between SOC scattering and inelastic scattering is revealed through a temperature-dependence study of MR, and the WAL-weak localization transition is at about 6 K. Furthermore, unambiguous results of the Kondo effect, nonlinear Hall, hysteresis loop, and Rashba SOC suggest the coexistence of WAL at the PAO/STO (Re = Pr) heterointerface with exchange coupling between the localized magnetic moment and the itinerant electron. These results pave a unique route for the exploration of spin-polarized 2DEGs at oxide heterointerfaces.
复杂氧化物异质界面提供了一个在破缺反演对称性下操纵自旋轨道耦合的平台。此外，由于强自旋轨道耦合，它们的弱反局域化（WAL）效应表现出量子相干行为。在此，我们突破了ReAlO/STO（Re = La、Pr、Nd、Sm和Gd）异质界面处晶格失配的限制，并通过旋涂获得了它们的二维电子气（2DEG）。研究了所得量子修正中不同Re元素对电导率的影响。观察到由于Re元素的电离势，异质界面的电导率随着原子序数的增加而降低。此外，在垂直或平行场中的磁电阻（MR）测量清楚地揭示了除SAO/STO（Re = Sm）和GAO/STO（Re = Gd）之外的ReAO/STO样品中存在强Rashba自旋轨道耦合（SOC），并且在2 K时，SOC的有效场（）从LAO/STO（Re = La， = 0.82 T）到NAO/STO（Re = Nd， = 1.37 T）逐渐增加。通过对MR的温度依赖性研究揭示了SOC散射和非弹性散射之间的竞争，并且WAL - 弱局域化转变发生在约6 K。此外，近藤效应、非线性霍尔、磁滞回线和Rashba SOC的明确结果表明在PAO/STO（Re = Pr）异质界面处WAL与局域磁矩和巡游电子之间的交换耦合共存。这些结果为探索氧化物异质界面处的自旋极化2DEG开辟了一条独特的途径。
