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Dynamic unidirectional anisotropy in cubic FeGe with antisymmetric spin-spin-coupling
Nicolas Josten1, Thomas Feggeler1, Ralf Meckenstock1
1Faculty of Physics and Center for Nanointegration (CENIDE), University Duisburg Essen, Duisburg, 47057, Germany.
Scientific Reports
|February 20, 2020
Summary
Strong unidirectional anisotropy was discovered in bulk B20 FeGe using ferromagnetic resonance spectroscopy. This dynamic effect, not seen in static measurements, may enable directed spin transport in chiral magnetic systems.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Bulk polycrystalline B20 FeGe is known to possess inherent Dzyaloshinskii-Moriya interaction.
- This interaction leads to nonreciprocal spin-wave dispersion, a key characteristic in chiral magnetic systems.
Purpose of the Study:
- To investigate and quantify the unidirectional anisotropy in bulk B20 FeGe.
- To explore the dynamic nature of this anisotropy and its potential applications.
Main Methods:
- Ferromagnetic resonance (FMR) spectroscopy was employed to measure the magnetic properties of B20 FeGe samples.
- X-band FMR was performed near the Curie temperature (276 K ± 1 K) on bulk samples.
- FMR was also conducted on micron-sized FeGe wedges at 293 K ± 2 K.
Main Results:
- Strong unidirectional anisotropy, with a value of KUD = 960 J/m³ ± 10 J/m³, was measured in bulk B20 FeGe.
- This anisotropy was observed dynamically via FMR and is not detectable through static magnetometry.
- Over 25 standing spin wave modes exhibiting unidirectional anisotropy were identified in micron-sized FeGe wedges.
Conclusions:
- Bulk B20 FeGe exhibits a significant, dynamically measurable unidirectional anisotropy previously unknown in bulk ferromagnets.
- The observed unidirectional anisotropy is linked to the inherent Dzyaloshinskii-Moriya interaction and nonreciprocal spin-wave dispersion.
- This finding opens new avenues for developing directed spin transport in chiral magnetic materials.
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