Cr2Te3 Thin Films for Integration in Magnetic Topological Insulator Heterostructures

Abstract

Chromium telluride compounds are promising ferromagnets for proximity coupling to magnetic topological insulators (MTIs) of the Cr-doped (Bi,Sb) 2 (Se,Te) 3 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 Cr 2 Te 3 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 Cr 2 Te 3 thin films. X-ray magnetic circular dichroism (XMCD) measured at the Cr L 2,3 edges gives information about the local electronic and magnetic structure of the Cr ions. We further demonstrate the overgrowth of Cr 2 Te 3 (001) thin films by high-quality Cr-doped Sb 2 Te 3 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 Cr 2 Te 3 thin films, and their integration into advanced MTI heterostructures for quantum device applications.

Recent Progress in Proximity Coupling of Magnetism to Topological Insulators

“…It was proposed that this type of proximity effect would be more efficient in heterostructures where the MM and TI have i) exactly the same or similar crystal structure, and ii) similar atomic composition. [ 93,125–129 ] However, thus far, a limited range of structures have been explored theoretically, and ab initio calculations are difficult for non‐commensurate structures, so it remains an open question how to optimize the heterostructures for magnetic extension. We will discuss this mechanism in detail in Section 3.1.4, in the context of layered FMI–TI heterostructures.…”

Free-standing 2D non-van der Waals antiferromagnetic hexagonal FeSe semiconductor: halide-assisted chemical synthesis and Fe2+ related magnetic transitions

“…9) and NbN 10 thin lms have been obtained by such methods, although the substrate may affect the magnetic and electrical properties, hindering the wide applications of such 2D nanostructures. [8][9][10] Therefore, it is urgent and signicant to prepare free-standing 2D magnetic nvdWs nanostructures. Regardless of the considerable interest, it is really difficult to obtain free-standing 2D nvdWs structures, which meant that the covalent bonds should be broken.…”

“…The 2D nvdWs magnetic nanostructures could be obtained on a substrate by the chemical vapor deposition method or molecular beam epitaxy method and the Cr 2 Te 3 (ref. 9 ) and NbN 10 thin films have been obtained by such methods, although the substrate may affect the magnetic and electrical properties, hindering the wide applications of such 2D nanostructures. 8–10 Therefore, it is urgent and significant to prepare free-standing 2D magnetic nvdWs nanostructures.…”

Two‐dimensional magnetic transition metal chalcogenides

“…With different amounts of Cr vacancies in the intercalated Cr layers, a range of Cr m X n with different stoichiometric ratios, such as CrX, Cr 2 X 3 , Cr 3 X 4 , Cr 5 X 8 , and CrTe 2 , can be formed, and behave as ferrimagnetic, antiferromagnetic, and ferromagnetic. Epitaxial Cr 2 S 3 , 58 CrSe, 56 CrTe 2 , 59 CrTe, 60 and Cr 2 Te 3 61–63 thin films with thicknesses down to several nanometers have been grown on various substrates (mica, SrTiO 3 , Si, Bi 2 Se 3 , and so on) by CVD and MBE, showing high Curie temperature T c (e.g., ~305 K for 8.7 nm CrTe 2 thin film 59 ), and promising electrical transport properties (e.g., unconventional anomalous Hall effect 60 ) for spintronic devices. The successful synthesis of 2D Cr 2 S 3 , 55,58 Cr 2 Te 3 , 57 and CrTe 2 26 with ML thickness (referring to the smallest repeating unit along the z ‐direction) have also been recently reported.…”