Unusual Electric and Optical Tuning of KTaO3-Based Two-Dimensional Electron Gases with 5d Orbitals,ACS Nano

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Unusual Electric and Optical Tuning of KTaO3-Based Two-Dimensional Electron Gases with 5d Orbitals
ACS Nano ( IF 15.8 ) Pub Date : 2019-01-03 00:00:00 , DOI: 10.1021/acsnano.8b07622
Hui Zhang _{1,

2} , Xi Yan _{1,

2} , Xuejing Zhang _{1,

2} , Shuai Wang ₃ , Changmin Xiong ₃ , Hongrui Zhang _{1,

2} , Shaojin Qi _{1,

2} , Jine Zhang _{1,

2} , Furong Han _{1,

2} , Ning Wu _{1,

2} , Banggui Liu _{1,

2} , Yuansha Chen _{1,

2} , Baogen Shen _{1,

2} , Jirong Sun _{1,

2}

Affiliation

Controlling electronic processes in low-dimension electron systems is centrally important for both fundamental and applied researches. While most of the previous works focused on SrTiO₃-based two-dimensional electron gases (2DEGs), here we report on a comprehensive investigation in this regard for amorphous-LaAlO₃/KTaO₃ 2DEGs with the Fermi energy ranging from ∼13 meV to ∼488 meV. The most important observation is the dramatic variation of the Rashba spin–orbit coupling (SOC) as Fermi energy sweeps through 313 meV: The SOC effective field first jumps and then drops, leading to a cusp of ∼2.6 T. Above 313 meV, an additional species of mobile electrons emerges, with a 50-fold enhanced Hall mobility. A relationship between spin relaxation distance and the degree of band filling has been established in a wide range. It indicates that the maximal spin precession length is ∼70.1 nm and the maximal Rashba spin splitting energy is ∼30 meV. Both values are much larger than the previously reported ones. As evidenced by density functional theory calculation, these unusual phenomena are closely related to the distinct band structure of the 2DEGs composed of 5d electrons. The present work further deepens our understanding of perovskite conducting interfaces, particularly those composed of 5d transition-metal oxides.

中文翻译：

具有5d轨道的基于KTaO ₃的二维电子气的异常电和光调谐

控制低维电子系统中的电子过程对于基础研究和应用研究都至关重要。尽管先前的大多数工作都集中在基于SrTiO ₃的二维电子气（2DEG）上，但我们在此报告了对非晶LaAlO ₃ / KTaO ₃的全面研究。2DEG的费米能范围为〜13 meV至〜488 meV。最重要的观察结果是当费米能量扫过313 meV时Rashba自旋-轨道耦合（SOC）发生剧烈变化：SOC有效场先跃升然后下降，导致尖端约为2.6T。在313 meV以上，出现了更多种类的移动电子，其霍尔迁移率提高了50倍。自旋弛豫距离和带填充程度之间的关系已经在很宽的范围内建立。这表明最大自旋进动长度为〜70.1 nm，最大Rashba自旋分裂能为〜30 meV。这两个值都比以前报告的值大得多。正如密度泛函理论计算所证明的那样，这些异常现象与由5d电子组成的2DEG的独特能带结构密切相关。

更新日期：2019-01-03

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