Cr_xPt_1–xTe₂ (x ≤ 0.45): A Family of Air-Stable and Exfoliatable van der Waals Ferromagnets

The development of thermally robust, air-stable, exfoliatable two-dimensional van der Waals ferromagnetic materials with high transition temperatures is of great importance. Here, we establish a family of magnetic alloys, Cr_xPt_1–xTe₂ (x ≤ 0.45), that combines the stability of the late transition metal dichalcogenide PtTe₂ with magnetism from Cr. These materials are easily grown in crystal form from the melt, are stable in ambient conditions, and have among the highest concentrations of magnetic element substitution in transition metal dichalcogenide alloys. The highest Cr-substituted material, Cr_0.45Pt_0.55Te₂, exhibits ferromagnetic behavior below 220 K, and the easy axis is along the c-axis of the material, as determined using a combination of neutron diffraction and magnetic susceptibility measurements. These materials are metallic, with appreciable magnetoresistance below the Curie temperature. Single-crystal and powder diffraction measurements indicate Cr readily alloys onto the Pt site and does not sit in the van der Waals space, allowing these materials to be readily exfoliated to the few-layer regime. In summary, this air-stable, exfoliatable, high transition temperature ferromagnet shows great potential as building block for future 2D devices.