In-plane magnetic domains and N\'eel-like domain walls in thin flakes of the room temperature CrTe$_2$ van der Waals ferromagnet

TL;DR

This study visualizes and characterizes room-temperature magnetic domains and domain walls in CrTe2 van der Waals ferromagnetic flakes, revealing in-plane flux-closure patterns, Ne9el-like walls, and size-dependent coercivity.

Contribution

It provides the first microscopic imaging of magnetic domains in CrTe2 at room temperature, demonstrating stable in-plane magnetic patterns and domain wall structures.

Findings

Magnetic domains are observable at room temperature in CrTe2 flakes.

Domain walls are likely Ne9el type with widths of tens of nanometers.

Coercivity increases as the volume of the flakes decreases.

Abstract

The recent discovery of magnetic van der Waals materials has triggered a wealth of investigations in materials science, and now offers genuinely new prospects for both fundamental and applied research. Although the catalogue of van der Waals 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 domains walls in micron-sized flakes of the CrTe$_2$ van der Waals ferromagnet. Flux-closure magnetic patterns suggesting in-plane six-fold symmetry are observed. Upon annealing the material above its Curie point (315 K), the magnetic domains disappear. By cooling back down 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 N\'eel texture, are preferentially oriented along directions separated by 120 degrees, 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 mT only, showing that the CrTe$_2$ compound is magnetically soft. The coercivity is found to increase as the volume of the material decreases.