Xu Yushuo, Wang Yuanyuan, Wang Shuhua, Yu Shiqiang, Huang Baibiao, Dai Ying, Wei Wei
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan250100, People's Republic of China.
Nano Lett. 2022 Nov 23;22(22):9147-9153. doi: 10.1021/acs.nanolett.2c03791. Epub 2022 Nov 11.
In order to achieve valley polarization, breaking the time-reversal symmetry in two-dimensional hexagonal lattices with inversion asymmetry is the heart of current valleytronic research, which, however, has caused studies to stagnate due to the inevitable drawbacks. In this work, we go beyond the conventional paradigm and demonstrate the novel valley physics caused by lowering the crystalline symmetry instead of breaking the time-reversal symmetry. In particular, we translate our concept into concrete nonmagnetic LaOMX monolayers with a tetragonal lattice, confirming that a spontaneous structure distortion can cause the long-sought, considerably large valley polarization. In detail, the physics of valley-orbital coupling, valley-orbital-layer coupling, valley-contrasting linear dichroism, and interlayer exciton valleytronics are discussed.
为了实现谷极化，在具有反演不对称性的二维六角晶格中打破时间反演对称性是当前谷电子学研究的核心，然而，由于不可避免的缺点，这导致了研究停滞不前。在这项工作中，我们超越了传统范式，证明了通过降低晶体对称性而非打破时间反演对称性所引发的新型谷物理现象。具体而言，我们将我们的概念转化为具有四方晶格的具体非磁性LaOMX单层，证实了自发结构畸变可导致长期以来寻求的相当大的谷极化。详细讨论了谷-轨道耦合、谷-轨道-层耦合、谷对比线性二色性和层间激子谷电子学的物理原理。
