  Achieving large-scale growth of two-dimensional (2D) ferromagnetic materials
with high Curie temperature (TC) and perpendicular magnetic anisotropy (PMA) is
highly desirable for the development of ultra-compact magnetic sensors and
magnetic memories. In this context, van der Waals (vdW) Cr2Te3 appears as a
promising candidate. Bulk Cr2Te3 exhibits strong PMA and a TC of 180 K.
Moreover, both PMA and TC might be adjusted in ultrathin films by engineering
composition, strain, or applying an electric field. In this work, we
demonstrate the molecular beam epitaxy (MBE) growth of vdW heterostructures of
five-monolayer quasi-freestanding Cr2Te3 on three classes of 2D materials:
graphene (semimetal), WSe2 (semiconductor) and Bi2Te3 (topological insulator).
By combining structural and chemical analysis down to the atomic level with ab
initio calculations, we confirm the single crystalline character of Cr2Te3
films on the 2D materials with sharp vdW interfaces. They all exhibit PMA and
TC close to the bulk Cr2Te3 value of 180 K. Ab initio calculations confirm this
PMA and show how its strength depends on strain. Finally, Hall measurements
reveal a strong anomalous Hall effect, which changes sign at a given
temperature. We theoretically explain this effect by a sign change of the Berry
phase close to the Fermi level. This transition temperature depends on the 2D
material in proximity, notably as a consequence of charge transfer. MBE-grown
Cr2Te3/2D material bilayers constitute model systems for the further
development of spintronic devices combining PMA, large spin-orbit coupling and
sharp vdW interface.
