# Fan-type spin structure in uni-axial chiral magnets

## TL;DR

This paper explores a rare fan-type spin modulation in uni-axial chiral magnets near transition temperatures, revealing its occurrence and underlying physics through phase diagram analysis and soliton behavior.

## Contribution

It identifies and analyzes a rare fan-type spin structure in chiral magnets, providing insights into its phase boundary and soliton dynamics.

## Key findings

- Fan-type modulation appears near transition temperatures.
- Fan structure occurs below the phase boundary of continuous transition.
- No isolated soliton solutions exist in the fan region.

## Abstract

We investigate the spin structure of a uni-axial chiral magnet near the transition temperatures in low fields perpendicular to the helical axis. We find a fan-type modulation structure where the clockwise and counterclockwise windings appear alternatively along the propagation direction of the modulation structure. This structure is often realized in a Yoshimori-type (non-chiral) helimagnet but it is rarely realized in a chiral helimagnet. To discuss underlying physics of this structure, we reconsider the phase diagram (phase boundary and crossover lines) through the free energy and asymptotic behaviors of isolated solitons. The fan structure appears slightly below the phase boundary of the continuous transition of instability-type. In this region, there are no solutions containing any types of isolated solitons to the mean field equations.