Phase engineering of Cr5Te8 with colossal anomalous Hall effect

Abstract

The development of intrinsic ferromagnetism in two-dimensional (2D) limit is at the core of ultra-compact spintronic applications. However, direct synthesis of non-layered 2D magnets with strong ferromagnetic order is still in infancy. Here we report the phasecontrollable synthesis of trigonal and monoclinic Cr5Te8 flakes via a facile chemical vapor deposition route. Both phases exhibit robust ferromagnetism with strong perpendicular anisotropy down to a few nanometers, as confirmed by both magneto-optical and 2 magnetotransport measurements. High Curie temperature up to 200 K is obtained by manipulating the phase structure and thickness. Remarkably, a colossal anomalous Hall effect is observed in the more distorted monoclinic Cr5Te8 with an enhanced anomalous Hall conductivity of 650 Ω -1 cm -1 and anomalous Hall angle of 5% achieved simultaneously. Our work paves the way for the scalable synthesis of 2D magnetic materials and highlights the great potential of Cr5Te8 for engineering future spintronic devices.

Recent Developments in Chemical Vapor Deposition of 2D Magnetic Transition Metal Chalcogenides

“…The CVD-grown material was unambiguously determined to be CrSe 2 . Very recently, by precisely examining the ADF-STEM image and intensity line profiles, differentiation of trigonal and monoclinic Cr 5 Te 8 was achieved (Figure f,g) . The atom-resolved structures play essential roles in understanding the phase-dependent magnetic properties, which will be discussed in the later parts.…”

“…Chromium chalcogenides (Cr m X n , X = S, Se, and Te) are recently emerging as a class of key materials due to their intriguing stoichiometry or composition-dependent magnetic properties. Cr m X n possesses a large number of binary compounds with various component ratios, such as Cr 2 S 3 , ,, CrSe, CrSe 2 , CrTe, Cr 2 Te 3 , , Cr 5 Te 8 , , and CrTe 2 . CrX 2 shares similar layered structures with the well-known transition metal dichalcogenides (e.g., MoS 2 , WTe 2 ), whereas the rest stoichiometric Cr m X n reveals nonlayered structures, which can be regarded as a self-intercalated compound with inserting additional Cr atoms into the van der Waals gap of CrX 2 .…”

“…(f,g) Simulated STEM images and intensity line profiles of trigonal and monoclinic Cr 5 Te 8 , respectively. Reproduced with permission from ref . Copyright 2022 Springer Nature.…”

“…However, the synthesis depends sensitively on the growth atmosphere such as temperature and carrier gas, in other words, a slight change in the environment may affect the sample formation and thickness significantly, which will be discussed in the later parts. Very recently, we have also demonstrated the successful synthesis of 2D Cr 5 Te 8 on the SiO 2 /Si substrate . The grown materials together with the SiO 2 /Si substrate were used directly for the fabrication of Hall bar devices.…”

“…Overview of this review including structure, synthesis, and property of magnetic 2D TMCs. Reproduced with permission from refs and − . Copyright 2019 Wiley-VCH .…”