Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe2 and 1T-NbSe2

• Published in: Nature communications Vol. 12; no. 1; p. 5873
• Main Authors: Nakata, Yuki, Sugawara, Katsuaki, Chainani, Ashish, Oka, Hirofumi, Bao, Changhua, Zhou, Shaohua, Chuang, Pei-Yu, Cheng, Cheng-Maw, Kawakami, Tappei, Saruta, Yasuaki, Fukumura, Tomoteru, Zhou, Shuyun, Takahashi, Takashi, Sato, Takafumi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07.10.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 147/138; 639/301/119/544; 639/766/119/995; Bandwidths; Charge density waves; Electrons; Graphene; High temperature; Humanities and Social Sciences; Hybridization; Interlayers; Monolayers; multidisciplinary; Perturbation; Photoexcitation; Physics; Quantum phenomena; Robustness; Room temperature; Science; Science (multidisciplinary); Superconductivity; Transition metal compounds; Transition temperature; Transition temperatures
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26105-1

Combination of low-dimensionality and electron correlation is vital for exotic quantum phenomena such as the Mott-insulating phase and high-temperature superconductivity. Transition-metal dichalcogenide (TMD) 1T-TaS 2 has evoked great interest owing to its unique nonmagnetic Mott-insulator nature coupled with a charge-density-wave (CDW). To functionalize such a complex phase, it is essential to enhance the CDW-Mott transition temperature T CDW-Mott , whereas this was difficult for bulk TMDs with T CDW-Mott  < 200 K. Here we report a strong-coupling 2D CDW-Mott phase with a transition temperature onset of ~530 K in monolayer 1T-TaSe 2 . Furthermore, the electron correlation derived lower Hubbard band survives under external perturbations such as carrier doping and photoexcitation, in contrast to the bulk counterpart. The enhanced Mott-Hubbard and CDW gaps for monolayer TaSe 2 compared to NbSe 2 , originating in the lattice distortion assisted by strengthened correlations and disappearance of interlayer hopping, suggest stabilization of a likely nonmagnetic CDW-Mott insulator phase well above the room temperature. The present result lays the foundation for realizing monolayer CDW-Mott insulator based devices operating at room temperature. Monolayer transition metal dechalcogenides are a promising platform to study the interplay of low-dimensionality and electron correlations. Here, the authors report a Mott insulator state in monolayer 1T-TaSe 2 , that survives far above room temperature and is robust against external perturbations.