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Double-Exchange Interaction in Optically Induced Nonequilibrium State: A Conversion from Ferromagnetic to
1Department of Physics, Tohoku University, Sendai 980-8578, Japan.
Physical Review Letters
|December 9, 2017
Summary
The double-exchange interaction, typically ferromagnetic, becomes antiferromagnetic in photoexcited states. This study reveals a hidden antiferromagnetic coupling under nonequilibrium conditions, converting metallic ferromagnets to antiferromagnets.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Materials Science
Background:
- The double-exchange (DE) interaction is a primary mechanism driving ferromagnetic (FM) order in materials.
- Understanding electron-spin coupling is crucial for designing novel magnetic states.
Purpose of the Study:
- To investigate the nature of the DE interaction in highly photoexcited states.
- To explore the transient dynamics of electron-spin coupling under nonequilibrium conditions.
- To identify mechanisms for switching magnetic states.
Main Methods:
- Analysis of transient dynamics involving quantum electrons and classical spins.
- Application of an AC field to a metallic FM state.
- Modeling electron-spin coupling under photoexcitation.
Main Results:
- The DE interaction exhibits antiferromagnetic (AFM) behavior in highly photoexcited states.
- An applied AC field can induce a transition from an FM to an AFM (Néel) state.
- The FM-to-AFM conversion time is dependent on light amplitude and frequency.
Conclusions:
- A hidden AFM interaction exists within the DE mechanism under nonequilibrium electron distributions.
- Photoexcitation provides a pathway to control and potentially switch magnetic ordering.
- This finding opens new avenues for manipulating magnetic properties in materials.
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