Tailoring magnetism in self-intercalated Cr 1 +δ Te 2 epitaxial films

Magnetic transition metal dichalcogenide (TMD) films have recently emerged as promising candidates in hosting novel magnetic phases relevant to next-generation spintronic devices. However, systematic control of the magnetization orientation, or anisotropy, and its thermal stability characterized by Curie temperature $({T}_{\\mathrm{C}})$, remains to be achieved in such films. Here we present self-intercalated epitaxial ${\\mathrm{Cr}}_{1+\\ensuremath{\\delta}}{\\mathrm{Te}}_{2}$ films as a platform for achieving systematic/smooth magnetic tailoring in TMD films. Using a molecular-beam epitaxy based technique, we have realized epitaxial ${\\mathrm{Cr}}_{1+\\ensuremath{\\delta}}{\\mathrm{Te}}_{2}$ films with smoothly tunable \\ensuremath{\\delta} over a wide range (0.33--0.82), while maintaining NiAs-type crystal structure. With increasing \\ensuremath{\\delta}, we found monotonic enhancement of ${T}_{\\mathrm{C}}$ from 160 to 350 K, and the rotation of magnetic anisotropy from out-of-plane to in-plane easy-axis configuration for fixed film thickness. Contributions from conventional dipolar and orbital moment terms are insufficient to explain the observed evolution of magnetic behavior with \\ensuremath{\\delta}. Instead, ab initio calculations suggest that the emergence of antiferromagnetic interactions with \\ensuremath{\\delta}, and its interplay with conventional ferromagnetism, may play a key role in the observed trends. This demonstration of tunable ${T}_{\\mathrm{C}}$ and magnetic anisotropy across room temperature in TMD films paves the way for engineering different magnetic phases for spintronic applications.