In-Plane Magnetic Domains and Néel-like Domain Walls in Thin Flakes of the Room Temperature CrTe₂ Van der Waals Ferromagnet

TLDR

Magnetic van der Waals materials have recently been discovered, but most have Curie temperatures below 300 K, limiting their practical use. The authors used element‑selective X‑ray magnetic imaging together with magnetic force microscopy to map room‑temperature domains and domain walls in micron‑sized CrTe₂ flakes. Room‑temperature imaging revealed flux‑closure six‑fold symmetric domains that vanish above 315 K and reappear with a different pattern upon cooling, while Néel‑type domain walls oriented 120° apart and tens‑of‑nanometer wide were observed; the material is magnetically soft with coercivity of a few millitesla that rises as the flake volume shrinks.

Abstract

The recent discovery of magnetic van der Waals (vdW) materials triggered a wealth of investigations in materials science and now offers genuinely new prospects for both fundamental and applied research. Although the catalog of vdW ferromagnets is rapidly expanding, most of them have a Curie temperature below 300 K, a notable disadvantage for potential applications. Combining element-selective X-ray magnetic imaging and magnetic force microscopy, we resolve at room temperature the magnetic domains and domain walls in micron-sized flakes of the CrTe2 vdW ferromagnet. Flux-closure magnetic patterns suggesting an in-plane six-fold symmetry are observed. Upon annealing the material above its Curie point (315 K), the magnetic domains disappear. By cooling back the sample, a different magnetic domain distribution is obtained, indicating material stability and lack of magnetic memory upon thermal cycling. The domain walls presumably have Néel texture, are preferentially oriented along directions separated by 120°, and have a width of several tens of nanometers. Besides microscopic mapping of magnetic domains and domain walls, the coercivity of the material is found to be of a few millitesla only, showing that the CrTe2 compound is magnetically soft. The coercivity is found to increase as the volume of the material decreases.