Room Temperature Ferromagnetism of Monolayer Chromium Telluride with Perpendicular Magnetic Anisotropy

Abstract

The realization of long‐range magnetic ordering in 2D systems can potentially revolutionize next‐generation information technology. Here, the successful fabrication of crystalline Cr3Te4 monolayers with room temperature (RT) ferromagnetism is reported. Using molecular beam epitaxy, the growth of 2D Cr3Te4 films with monolayer thickness is demonstrated at low substrate temperatures (≈100 °C), compatible with Si complementary metal oxide semiconductor technology. X‐ray magnetic circular dichroism measurements reveal a Curie temperature (Tc) of v344 K for the Cr3Te4 monolayer with an out‐of‐plane magnetic easy axis, which decreases to v240 K for the thicker film (≈7 nm) with an in‐plane easy axis. The enhancement of ferromagnetic coupling and the magnetic anisotropy transition is ascribed to interfacial effects, in particular the orbital overlap at the monolayer Cr3Te4/graphite interface, supported by density‐functional theory calculations. This work sheds light on the low‐temperature scalable growth of 2D nonlayered materials with RT ferromagnetism for new magnetic and spintronic devices.

Van der Waals Superstructure and Twisting in Self-Intercalated Magnet with Near Room-Temperature Perpendicular Ferromagnetism

“…This is, however, not the case in our nanoplates as the majority of them are in the range of 10–70 nm thick (Figure c), as characterized by atomic force microscopy. The magnetization measurements as a function of applied magnetic field (Figure e and Figure S1) show a rapid increase in the initial magnetization when the field is applied parallel to the c -axis compared to when the field is applied perpendicular to the c -axis, implying there is perpendicular magnetic anisotropy with the easy axis along the c -axis, which is common for many chromium tellurides. ,, Compared to Cr 2 Te 3, which has a strong perpendicular magnetic anisotropy with an easy c -axis, , the perpendicular magnetic anisotropy on our nanoplates is relatively weak. Collectively, this demonstrates that the nanoplates studied here are indeed a different phase of chromium telluride than Cr 2 Te 3 .…”

“…It is worth mentioning, however, there are discrepancies in the literature regarding the magnetic properties of the same respective compounds. Indeed, varied T c values were reported in the same compounds of similar thickness (e.g., T c = 210 K versus 300 K for ∼9 nm thick CrTe 2 ), and in contrast to the anomalous thickness dependence previously discussed, other studies (i.e., 1T-CrTe 2 , Cr 3 Te 4 , and CrTe) suggested the absence of ,,,− or an opposite thickness dependence where the T c decreases with decreasing thickness . Since magnetism in bulk Cr 1+δ Te 2 is strongly dependent on the composition, ,,,,− the varied and sometimes contrasting magnetic properties of nanoplates and thin films may result from precisely how the excess Cr atoms are intercalated in the vdW gap; therefore, it is essential to correlate the magnetic phases with the details of Cr-intercalation to understand the intrinsic magnetism in this newly emerged vdW magnet family.…”

Recent Progress of Atomic Layer Technology in Spintronics: Mechanism, Materials and Prospects

“…According to the results of their research, Wong et al created a monolayer of VSe 2 on highly oriented pyrolytic graphite (HOPG) using MBE to seek for novel low-dimensional quantum phenomena [8,9]. MBE was used to build a room temperature ferromagnetic monolayer Cr 3 Te 4 in 2021 by Chua et al at a lower substrate temperature [10]. In conclusion, these findings demonstrate that MBE is still a highly successful and important method for generating thin films at the atomic layer level.…”

Ultrathin Van der Waals Antiferromagnet CrTe3 for Fabrication of In‐Plane CrTe3/CrTe2 Monolayer Magnetic Heterostructures

“…Chromium tellurides are a family of compounds with a complex binary phase diagram. [43] Among the chromium telluride family, ultrathin CrTe 2 , [44][45][46] Cr 2 Te 3 , [47,48] and Cr 3 Te 4 [49] have recently been demonstrated to be ferromagnetic vdW materials. CrTe 3 is also a typical vdW layered material [50,51] and its bulk form was recently identified to be an antiferromagnetic semiconductor containing layers made of lozenge-shaped Cr 4 tetramers.…”