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Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
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Band Structure of Helimagnons in MnSi Resolved by Inelastic Neutron Scattering
M Kugler1,2, G Brandl1,2, J Waizner3
1Physik-Department E21, Technische Universität München, 85748 Garching, Germany.
Physical Review Letters
|September 16, 2015
Summary
Spin waves called helimagnons in magnetic crystals exhibit band gaps due to their helical structure. This study resolves their band structure using neutron scattering, revealing localized and dispersing bands.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Magnetic crystals can form helical structures, creating a one-dimensional magnetic crystal.
- Spin-wave excitations, known as helimagnons, interact with this helical periodicity.
Purpose of the Study:
- To experimentally resolve the band structure of helimagnons in a magnetic helix.
- To investigate the effect of Bragg scattering on helimagnon propagation.
Main Methods:
- High-resolution inelastic neutron scattering.
- Preparation of a single crystal of MnSi in a single magnetic-helix domain.
Main Results:
- Identification of at least five helimagnon bands.
- Observation of a crossover from flat, localized bands at low energies to dispersing bands at higher energies.
- The low-energy helimagnon spectrum is described by a universal theory.
Conclusions:
- The band structure of helimagnons is successfully resolved.
- A parameter-free theory accurately describes the low-energy spectrum.
- Quantitative agreement across the energy range is achieved with a single fitting parameter.
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