Robust nature of the chiral spin helix in CrNb3S6 nanostructures studied by off-axis electron holography

Abstract

Magnetic soliton crystals with layered structures that host periodic chiral helimagnetic ordering are promising candidates for spintronic nanodevices. Among them, helimagnetic $\mathrm{Cr}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$ is unique owing to its crystallographic chirality and monoaxial Dzyaloshinskii-Moriya interaction. It is crucial to explore its magnetic configurations and properties with respect to the temperature and thickness, especially in reduced dimensions. Here, the chiral helimagnetic ground state in $\mathrm{Cr}{\mathrm{Nb}}_{3}{\mathrm{S}}_{6}$ nanostructures is investigated using off-axis electron holography in the transmission electron microscope. The period of the helical state is found to be independent of both temperature and specimen thickness, while the temperature dependence of the saturation magnetization is shown to follow a classical Heisenberg spin model. Monte Carlo simulations based on a discrete classical Heisenberg model reproduce the experimental observations closely, confirming the applicability of a three-dimensional Heisenberg model even in a confined specimen geometry.