Enhanced Ferromagnetism in Cr₂Te₃ via Topological Insulator Coupling

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. In this talk, we present the realization of wafer-scale Cr₂Te₃ down to 1 unit cell (u.c.) on insulating SrTiO₃(111) and/or Al₂O₃(0001) substrates using molecular beam epitaxy. Robust ferromagnetism emerges in 1 u.c. Cr₂Te₃ with a Curie temperature <i>T</i>_C = 100 K. Moreover, when Cr2Te3 is proximitized with topological insulator (TI) (Bi,Sb)₂Te₃, the magnetism becomes stronger – with <i>T</i>_C boosted to 135 K. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely a universal aspect of <i>T</i>_C 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.