Enhanced Ferromagnetism in Monolayer Cr2Te3 via Topological Insulator Coupling

TL;DR

This study demonstrates that coupling monolayer Cr2Te3 with topological insulators significantly enhances its ferromagnetic properties, with potential applications in topological electronics and quantum hybrid systems.

Contribution

It reports the first wafer-scale synthesis of monolayer Cr2Te3 and shows how topological insulator coupling boosts its Curie temperature and magnetization.

Findings

Curie temperature of 2ML Cr2Te3 increases to ~120 K when coupled with topological insulators.

Robust ferromagnetism persists in monolayer Cr2Te3.

Topological-surface-enhanced magnetism observed in 2D TMCs.

Abstract

Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D) ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered magnetic transition metal chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report the realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating SrTiO3(111) and/or Al2O3(001) substrates using molecular beam epitaxy. Robust ferromagnetism persists in the 2D limit. In particular, the Curie temperature TC of 2 ML Cr2Te3 increases from 100 K to ~ 120 K when proximitized to topological insulator (TI) (Bi,Sb)2Te3, with substantially boosted magnetization as observed via polarized neutron reflectometry. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely universal underlying TC enhancement in TI-coupled magnetic heterostructures. The topological-surface-enhanced magnetism in 2D TMC enables further exchange coupling physics and quantum hybrid studies, including paving the way to realize interface-modulated topological electronics.