CrTe Thin Films for Integration in Magnetic Topological Insulator Heterostructures.

Chromium telluride compounds are promising ferromagnets for proximity coupling to magnetic topological insulators (MTIs) of the Cr-doped (Bi,Sb)(Se,Te) class of materials as they share the same elements, thus simplifying thin film growth, as well as due to their compatible crystal structure. Recently, it has been demonstrated that high quality (001)-oriented CrTe thin films with perpendicular magnetic anisotropy can be grown on c-plane sapphire substrate. Here, we present a magnetic and soft x-ray absorption spectroscopy study of the chemical and magnetic properties of CrTe thin films. X-ray magnetic circular dichroism (XMCD) measured at the Cr L edges gives information about the local electronic and magnetic structure of the Cr ions. We further demonstrate the overgrowth of CrTe (001) thin films by high-quality Cr-doped SbTe films. The magnetic properties of the layers have been characterized and our results provide a starting point for refining the physical models of the complex magnetic ordering in CrTe thin films, and their integration into advanced MTI heterostructures for quantum device applications.