Tailoring magnetism in self-intercalated <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Cr</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Te</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> epitaxial films
Y. Fujisawa, M. Pardo-Almanza, J. Garland, K. Yamagami, X. Zhu, X. Chen, K. Araki, T. Takeda, M. Kobayashi, Y. Takeda, C. H. Hsu, F. C. Chuang, R. Laskowski, K. H. Khoo, A. Soumyanarayanan, Y. Okada
Abstract
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.