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

arXiv · 2110.03885

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

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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 TCDW-Mott, whereas this was difficult for bulk TMDs with TCDW-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.

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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. 2021-10-08. Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe2 and 1T-NbSe2. https://doi.org/10.1038/s41467-021-26105-1

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