Ferromagnetism and correlated insulating states in monolayer Mo33Te56

TL;DR

This paper reports the discovery of a new monolayer Mo33Te56 structure with kagome lattice geometry, exhibiting ferromagnetism and correlated insulating states, advancing the understanding of flat-band physics in two-dimensional materials.

Contribution

It introduces a novel monolayer kagome material with experimentally observed ferromagnetism and correlated insulator behavior, providing a clearer platform for flat-band physics exploration.

Findings

Kagome lattice geometry confirmed in monolayer Mo33Te56

Observation of ferromagnetism via spin-polarized STM

Detection of a correlated insulating state with a 15 meV gap

Abstract

Kagome lattices have an inherent two-dimensional nature. Despite previous realizations in the monolayer limit, their abilities to drive emergent electronic states such as correlated insulators have remained unobserved. Here, we report the experimental realization of a new structural phase of monolayer Mo33Te56, characterized by its virtually global uniformity as a mirror-twin boundary loop superlattice embedded in an H-MoTe2 monolayer. Through a combination of scanning tunnelling microscopy (STM) and theoretical calculations, we unveil a kagome geometry along with multiple associated sets of kagome flat bands. Crucially, the partial filling of these kagome bands induces ferromagnetism as revealed by spin-polarized STM, and leads to a correlated insulating state exhibiting a hard gap as large as 15 meV. Our findings represent a major advance in kagome materials, offering a framework with clearer band structures and more intrinsic two-dimensional properties for exploring flat-band physics.