Visualizing Exotic Orbital Texture in the Single-Layer Mott Insulator 1T-TaSe2

TL;DR

This study combines experimental and theoretical methods to reveal how strong electron correlations induce a Mott insulating state with unique orbital textures in single-layer 1T-TaSe2, a promising 2D platform for correlation physics.

Contribution

It demonstrates the existence of a robust Mott insulator with exotic orbital textures in single-layer 1T-TaSe2, and shows how interlayer coupling affects this state.

Findings

Single-layer 1T-TaSe2 exhibits a strong Mott insulating state.

Orbital texture is a key feature of the Mott phase.

Interlayer coupling reduces the energy gap and orbital texture.

Abstract

Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of novel Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunneling microscopy and angle-resolved photoemission. Our combined experimental and theoretical study indicates that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by novel orbital texture. Inclusion of interlayer coupling weakens the insulating phase in 1T-TaSe2, as seen by strong reduction of its energy gap and quenching of its correlation-driven orbital texture in bilayer and trilayer 1T-TaSe2. Our results establish single-layer 1T-TaSe2 as a useful new platform for investigating strong correlation physics in two dimensions.