# Unidirectional anisotropy in cubic FeGe with antisymmetric spin-spin-coupling

## TL;DR

This study reveals strong unidirectional anisotropy in bulk FeGe with antisymmetric spin-spin coupling, observed via ferromagnetic resonance and microscopy, highlighting novel magnetic behaviors near room temperature and at the skyrmion lattice phase.

## Contribution

It demonstrates the presence of unidirectional anisotropy in bulk FeGe with antisymmetric spin interactions, a phenomenon previously unreported in such materials.

## Key findings

- Unidirectional anisotropy measured at 1153 J/m^3 in primary mode
- Observation of 25 standing spin wave modes with anisotropy
- Detection of skyrmion lattice at 190 K in FeGe

## Abstract

We report strong unidirectional anisotropy in bulk polycrystalline B20 FeGe measured by ferromagnetic resonance spectroscopy. Bulk and micron-sized samples were produced and analytically characterized. FeGe is a B20 compound with inherent Dzyaloshinskii-Moriya interaction. Lorenz microscopy confirms a skyrmion lattice at $190 \; \text{K}$ in a magnetic field of 150 mT. Ferromagnetic resonance was measured at $276 \; \text{K} \pm 1 \; \text{K}$, near the Curie temperature. Two resonance modes were observed, both exhibit a unidirectional anisotropy of $K=1153 \; \text{J/m}^3 \pm 10 \; \text{J/m}^3$ in the primary, and $K=28 \; \text{J/m}^3 \pm 2 \; \text{J/m}^3$ in the secondary mode, previously unknown in bulk ferromagnets. Additionally, about 25 standing spin wave modes are observed inside a micron-sized FeGe wedge, measured at room temperature ($\sim \; 293$ K). These modes also exhibit unidirectional anisotropy.