Hwang Jinwoong, Kim Kyoo, Zhang Canxun, Zhu Tiancong, Herbig Charlotte, Kim Sooran, Kim Bongjae, Zhong Yong, Salah Mohamed, El-Desoky Mohamed M, Hwang Choongyu, Shen Zhi-Xun, Crommie Michael F, Mo Sung-Kwan
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Department of Physics, Pusan National University, Busan, South Korea.
Nat Commun. 2022 Feb 16;13(1):906. doi: 10.1038/s41467-022-28542-y.
Monolayers of two-dimensional van der Waals materials exhibit novel electronic phases distinct from their bulk due to the symmetry breaking and reduced screening in the absence of the interlayer coupling. In this work, we combine angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy to demonstrate the emergence of a unique insulating 2 × 1 dimer ground state in monolayer 1T-IrTe that has a large band gap in contrast to the metallic bilayer-to-bulk forms of this material. First-principles calculations reveal that phonon and charge instabilities as well as local bond formation collectively enhance and stabilize a charge-ordered ground state. Our findings provide important insights into the subtle balance of interactions having similar energy scales that occurs in the absence of strong interlayer coupling, which offers new opportunities to engineer the properties of 2D monolayers.
由于对称性破缺以及在没有层间耦合时屏蔽作用减弱，二维范德华材料的单层表现出与它们的体相不同的新型电子相。在这项工作中，我们结合角分辨光电子能谱和扫描隧道显微镜/能谱，来证明在单层1T-IrTe中出现了一种独特的绝缘2×1二聚体基态，与该材料的金属双层到体相形式相比，它具有较大的带隙。第一性原理计算表明，声子和电荷不稳定性以及局部键的形成共同增强并稳定了电荷有序基态。我们的发现为在没有强层间耦合时发生的具有相似能量尺度的相互作用之间的微妙平衡提供了重要见解，这为设计二维单层的性质提供了新的机会。
