Kinga Lasek, Paula M. Coelho, Pierluigi Gargiani, et al.
Appl. Phys. Rev. 9, 011409 (2022)
Cr(1þd)Te2 are pseudo-layered compounds consisting of CrTe2 transition metal dichalcogenide (TMD) layers with additional (d) selfintercalated Cr atoms. The recent search for ferromagnetic 2D materials revived the interest into chromium tellurides. Here, Cr(1þd)Te2 nanolayers are epitaxially grown on MoS2 (0001), forming prototypical van der Waals heterostructures. Under optimized growth conditions, ultrathin films of only two TMD layers with a single intercalated Cr-layer are achieved, forming a 2D sheet with van der Waals surfaces. Detailed compositional and structural characterization by scanning tunneling microscopy, grazing incidence x-ray diffraction, and highresolution Rutherford backscattering indicate the layer-by-layer growth and that the d can be tuned by post-growth annealing in a range between 0.5 and 1. X-ray magnetic circular dichroism and magnetometry measurements demonstrate that all self-intercalated Cr(1þd)Te2 nanolayers exhibit strong ferromagnetism with magnetic moments larger than 3lB per Cr-atom. The magnetic properties are maintained in the ultrathin limit of a material with a single intercalation layer. Interestingly, the magnetic anisotropy can be tuned from close to isotropic (d ¼ 1) to a desirable perpendicular anisotropy for low d values. Thus, the bottom-up growth of these 2D Cr(1þd)Te2 sheets is a promising approach for designing magnetic van der Waals heterostructures.
