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 190K in a magnetic field of 150 mT. Ferromagnetic resonance was measured at 276K±1K, near the Curie temperature. Two resonance modes were observed, both exhibit a unidirectional anisotropy of K=1153J/m3±10J/m3 in the primary, and K=28J/m3±2J/m3 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 (∼293 K). These modes also exhibit unidirectional anisotropy.
@article{arxiv.1902.02665,
title = {Unidirectional anisotropy in cubic FeGe with antisymmetric spin-spin-coupling},
author = {Nicolas Josten and Thomas Feggeler and Detlef Spoddig and Iliya Radulov and Marina Spasova and Ke Chai and Zi-An Li and Ralf Meckenstock and Oliver Gutfleisch and Michael Farle and Benjamin Zingsem},
journal= {arXiv preprint arXiv:1902.02665},
year = {2020}
}