Monolayer 1T-NbSe2 as a 2D-correlated magnetic insulator

Date
2021-11-19
Authors
Liu, Mengke
Leveillee, Joshua
Lu, Shuangzan
Yu, Jia
Kim, Hyunsue
Tian, Cheng
Shi, Youguo
Lai, Keji
Zhang, Chendong
Giustino, Feliciano
Journal Title
Journal ISSN
Volume Title
Publisher
American Association for the Advancement of Science
Abstract

Monolayer group V transition metal dichalcogenides in their 1T phase have recently emerged as a platform to investigate rich phases of matter, such as spin liquid and ferromagnetism, resulting from strong electron correla- tions. Newly emerging 1T-NbSe2 has inspired theoretical investigations predicting collective phenomena such as charge transfer gap and ferromagnetism in two dimensions; however, the experimental evidence is still lacking. Here, by controlling the molecular beam epitaxy growth parameters, we demonstrate the successful growth of high-quality single-phase 1T-NbSe2. By combining scanning tunneling microscopy/spectroscopy and ab initio calculations, we show that this system is a charge transfer insulator with the upper Hubbard band located above the valence band maximum. To demonstrate the electron correlation resulted magnetic property, we create a vertical 1T/2H NbSe2 heterostructure, and we find unambiguous evidence of exchange interactions between the localized magnetic moments in 1T phase and the metallic/superconducting phase exemplified by Kondo reso- nances and Yu-Shiba-Rusinov–like bound states.

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Citation
Mengke Liu et al. ,Monolayer 1T-NbSe2 as a 2D-correlated magnetic insulator.Sci. Adv.7,eabi6339(2021).DOI:10.1126/sciadv.abi6339