Zhang Shuhui, Wang Yuanyuan, Wang Shuhua, Huang Baibiao, Dai Ying, Wei Wei
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China.
J Phys Chem Lett. 2021 Mar 11;12(9):2245-2251. doi: 10.1021/acs.jpclett.1c00149. Epub 2021 Feb 26.
In this work, the novel electronic properties of the Janus TiClI monolayer (ML) and van der Waals (vdW) bilayers (BLs) have been demonstrated. As a result of the strong spin-orbit coupling (SOC) together with the inversion symmetry breaking, the TiClI ML shows valley spin splitting of 62.67 meV at the K/K' point. In magnetic V- and Cr-doped TiClI MLs, sizable valley polarization of 36.70 and 45.35 meV occurs, respectively. TiClI vdW BLs indicate typical type-II band alignment with a quite large band offset (>500 meV), and interestingly, the interlayer-polarization is almost 100% for all considered stacking orders. In addition, the interlayer-polarization is insensitive to the interlayer distance. In this situation, the interlayer exciton and valley polarization lifetimes could be prolonged, and thus, TiClI vdW BLs provide new opportunities for light-energy conversion and valleytronics. As the interlayer distance decreases, the TiClI BLs of AB' and AB stacking indicate a semiconductor-to-metal transition and are characterized by hole-doping, and the doping concentration can be further tuned by changing the interlayer distance.
在这项工作中，已证明了Janus TiClI单层（ML）和范德华（vdW）双层（BLs）的新型电子特性。由于强自旋轨道耦合（SOC）以及反演对称性破缺，TiClI ML在K/K'点处显示出62.67 meV的谷自旋分裂。在磁性V掺杂和Cr掺杂的TiClI ML中，分别出现了36.70和45.35 meV的可观谷极化。TiClI vdW BLs表现出典型的II型能带排列，具有相当大的带隙（>500 meV），有趣的是，对于所有考虑的堆叠顺序，层间极化几乎为100%。此外，层间极化对层间距离不敏感。在这种情况下，层间激子和谷极化寿命可以延长，因此，TiClI vdW BLs为光能转换和谷电子学提供了新的机会。随着层间距离减小，AB'和AB堆叠的TiClI BLs表现出半导体到金属的转变，并以空穴掺杂为特征，并且掺杂浓度可以通过改变层间距离进一步调节。
