Alternating-Chiral Charge Density Waves and Hybrid Ferrimagnetism in Monolayered NbTe2

TL;DR

This study uncovers a novel chiral charge density wave order in monolayer NbTe2, revealing intertwined lattice, charge, and spin phenomena with potential for chiral spintronic applications.

Contribution

It demonstrates the existence of alternating-chiral charge density waves and hybrid ferrimagnetism in monolayer NbTe2, combining experimental and theoretical insights into their origin and properties.

Findings

Chiral charge density waves with opposite handedness identified.

Emergent spin polarization synchronized with chiral order.

Correlation-driven origin of intertwined orders confirmed by first-principles calculations.

Abstract

Intertwining of different quantum degrees of freedom manifests exotic quantum phenomena in many-body systems, especially in reduced dimensionality. Here we show that monolayered NbTe2 serves as an ideal platform where lattice, charge, and spin degrees of freedom manifest cooperatively, leading to a new and threading order of chirality. By using spin-polarized scanning tunneling microscopy/spectroscopy, we reveal that the root19 * root19 phase of NbTe2 is encoded with both alternating-chiral atomic displacements and charge density waves, characterized by two chiral units of opposite handedness within the reconstructed cell. We show unambiguous evidence for emergent spin polarizations spreading over the primitive cell, with the magnetization orientation synchronized with alternating handedness of chiral order. Our first-principles studies identify the origin of intertwined orders being correlation driven, with the threading order of chirality emerging when the on-site Coulomb repulsion exceeds a critical value. The spin ordering is further shown to be of hybrid ferrimagnetic nature, contributed by the itinerant electrons and localized d-orbitals. Collectively, these findings expand the realm of chiral order in correlated electron systems, and facilitate an appealing platform for chiral spintronic and related applications.