1. Signatures of the exciton gas phase and its condensation in monolayer 1T-ZrTe2
- Author
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Song, Yekai, Jia, Chunjing, Xiong, Hongyu, Wang, Binbin, Jiang, Zhicheng, Huang, Kui, Hwang, Jinwoong, Li, Zhuojun, Hwang, Choongyu, Liu, Zhongkai, Shen, Dawei, Sobota, Jonathan A, Kirchmann, Patrick, Xue, Jiamin, Devereaux, Thomas P, Mo, Sung-Kwan, Shen, Zhi-Xun, and Tang, Shujie
- Subjects
Quantum Physics ,Physical Sciences ,Condensed Matter Physics - Abstract
The excitonic insulator (EI) is a Bose-Einstein condensation (BEC) of excitons bound by electron-hole interaction in a solid, which could support high-temperature BEC transition. The material realization of EI has been challenged by the difficulty of distinguishing it from a conventional charge density wave (CDW) state. In the BEC limit, the preformed exciton gas phase is a hallmark to distinguish EI from conventional CDW, yet direct experimental evidence has been lacking. Here we report a distinct correlated phase beyond the 2×2 CDW ground state emerging in monolayer 1T-ZrTe2 and its investigation by angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). The results show novel band- and energy-dependent folding behavior in a two-step process, which is the signatures of an exciton gas phase prior to its condensation into the final CDW state. Our findings provide a versatile two-dimensional platform that allows tuning of the excitonic effect.
- Published
- 2023