Magnetic evolution of Cr₂Te₃ epitaxially grown on graphene with post-growth annealing

Two-dimensional and van der Waals ferromagnets are ideal platform to study low dimensional magnetism and proximity effects in van der Waals heterostructures. Their ultimate two dimensional character offers also the opportunity to easily adjust their magnetic properties using strain or electric fields. Among 2D ferromagnets, the Cr₁₊ₓTe₂ compounds with x=0-1 are very promising because their magnetic properties depend on the amount of self-intercalated Cr atoms between pure CrTe₂ layers and the Curie temperature (TC) can reach room temperature for certain compositions. Here, we investigate the evolution of the composition, structural and magnetic properties of thin Cr1.33Te₂ (Cr₂Te₃) films epitaxially grown on graphene upon annealing. We observe a transition above 450{}C from the Cr1.33Te₂ phase with perpendicular magnetic anisotropy and a TC of 180 K to a composition close to Cr1.39Te₂ with in-plane magnetic anisotropy and a TC of 240-250 K. This phase remains stable up to 650{}C above which a pure Cr film starts to form. This work demonstrates the complex interplay between intercalated Cr, lattice parameters and magnetic properties in Cr₁₊ₓTe₂ compounds.