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

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 correlations. Although 1T phase NbSe2 does not occur naturally in bulk form, it has been discovered that the 1T and 1H phases can coexist when monolayer NbSe2 is grown via molecular beam epitaxy (MBE). This discovery has inspired theoretical investigations predicting collective phenomena such as ferromagnetism in two dimensions. Here, by controlling the MBE growth parameters, we demonstrate the successful growth of 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. Furthermore, by creating a vertical 1T/2H NbSe2 heterostructure, we find evidence of exchange interactions between the localized magnetic moments in 1T phase and the metallic/superconducting phase, as manifested by Kondo resonances and Yu-Shiba-Rusinov bound states.

References in corpus (5)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Fermi-liquid instabilities at magnetic quantum phase transitions
• Gate-tunable Phase Transitions in 1T-TaS${}_2$
• Abundance of correlated insulating states at fractional fillings of WSe${}_2$/WS${}_2$ moiré superlattices
• Direct identification of Mott Hubbard band pattern beyond charge density wave superlattice in monolayer 1T-NbSe2

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• Revealing the Charge Density Wave Proximity Effect in Graphene on 1T-TaS${}_2$
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• Doped Mott phase and charge correlations in monolayer 1T-NbSe${}_2$
• Controlling magnetic frustration in 1T-TaS${}_2$ via Coulomb engineered long-range interactions
• Magnetic order through Kondo coupling to quantum spin liquids
• Emergent Quantum Phenomena of Noncentrosymmetric Charge-Density Wave in 1T-Transition Metal Dichalcogenides
• Comment on "Identification of the Mott Insulating Charge Density Wave State in $1T$-TaS${}_2$"
• Topical review: the nature of the ground state and possibility of a quantum spin liquid in 1T metal dichalcogenides