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Giant magnetoelastic coupling in a metallic helical metamagnet
A Barcza1, Z Gercsi, K S Knight
1Department of Materials Science and Metallurgy, University of Cambridge, New Museums Site, Pembroke Street, Cambridge, CB2 3QZ, United Kingdom.
Physical Review Letters
|September 28, 2010
Summary
The thermal expansion of the helimagnetic state in Cobalt Manganese Silicon (CoMnSi) shows a record 2% change in interatomic distances. This discovery reveals a new mechanism for large magnetoelastic effects in metallic magnets.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Helimagnetic states in metallic magnets are known to exhibit thermal expansion.
- Magnetoelastic effects are crucial for understanding material properties under magnetic fields.
- Spin-orbit coupling is typically considered essential for significant magnetoelastic effects.
Purpose of the Study:
- To investigate the thermal evolution of the helimagnetic state in CoMnSi.
- To quantify the associated changes in interatomic distances.
- To elucidate the underlying mechanism for observed magnetoelastic effects.
Main Methods:
- High-resolution neutron diffraction
- Capacitance dilatometry
Main Results:
- Observed a thermal evolution of the helimagnetic state in CoMnSi.
- Measured interatomic distance changes up to 2%, the largest in a metallic magnet.
- Identified competing exchange interactions and anisotropic thermal expansion.
Conclusions:
- The study reveals a novel mechanism for large magnetoelastic effects in metallic magnets.
- This mechanism does not rely on strong spin-orbit coupling.
- CoMnSi serves as a model system for understanding these effects.
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