Crossover of skyrmion and helical modulations in noncentrosymmetric ferromagnets

TL;DR

This paper explores how the interplay between twisting and longitudinal modulations near the ordering temperature affects skyrmion structures and their evolution in noncentrosymmetric ferromagnets, revealing complex transformation processes.

Contribution

It uncovers the role of longitudinal modulations in skyrmion state transformations and their influence on magnetic phase behavior in noncentrosymmetric ferromagnets.

Findings

First-order processes dominate skyrmion transformations near the ordering temperature.

Longitudinal modulations significantly influence skyrmion lattice evolution.

Similar phenomena are observed in various chiral magnetic materials.

Abstract

The coupling between angular (twisting) and longitudinal modulations arising near the ordering temperature of noncentrosymmetric ferromagnets strongly influences the structure of skyrmion states and their evolution in an applied magnetic field. In the precursor states of cubic helimagnets, a continuous transformation of skyrmion lattices into the saturated state is replaced by the first-order processes accompanied by the formation of multidomain states. Recently the effects imposed by dominant longitudinal modulations have been reported in bulk MnSi and FeGe. Similar phenomena can be observed in the precursor regions of cubic helimagnet epilayers and in easy-plane chiral ferromagnets (e.g. in the hexagonal helimagnet CrNb3S6).