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

Yuki Nakata; Katsuaki Sugawara; Ashish Chainani; Hirofumi Oka; Changhua Bao; Shaohua Zhou; Pei-Yu Chuang; Cheng-Maw Cheng; Tappei Kawakami; Yasuaki Saruta; Tomoteru Fukumura; Shuyun Zhou; Takashi Takahashi; Takafumi Sato

doi:10.1038/s41467-021-26105-1

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

Nat Commun. 2021 Oct 7;12(1):5873. doi: 10.1038/s41467-021-26105-1.

Authors

Yuki Nakata¹, Katsuaki Sugawara^{1

2

3}, Ashish Chainani⁴, Hirofumi Oka³, Changhua Bao⁵, Shaohua Zhou⁵, Pei-Yu Chuang⁴, Cheng-Maw Cheng⁴, Tappei Kawakami¹, Yasuaki Saruta¹, Tomoteru Fukumura⁶, Shuyun Zhou^{5

7}, Takashi Takahashi^{1

2

3}, Takafumi Sato^{8

9

10}

Affiliations

¹ Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
² Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.
³ Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan.
⁴ National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC.
⁵ State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China.
⁶ Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
⁷ Frontier Science Center for Quantum Information, Beijing, 100084, China.
⁸ Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan. t-sato@arpes.phys.tohoku.ac.jp.
⁹ Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan. t-sato@arpes.phys.tohoku.ac.jp.
¹⁰ Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan. t-sato@arpes.phys.tohoku.ac.jp.

Abstract

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-TaS₂ 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-TaSe₂. 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 TaSe₂ compared to NbSe₂, 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.

Abstract

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