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Scattering theory of gilbert damping
Arne Brataas1, Yaroslav Tserkovnyak, Gerrit E W Bauer
1Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. Arne.Brataas@ntnu.no
Physical Review Letters
|September 4, 2008
Summary
This study uses scattering theory to analyze ferromagnet magnetization dynamics. It recovers the Landau-Liftshitz-Gilbert equation and details energy dissipation mechanisms.
Area of Science:
- Condensed matter physics
- Quantum mechanics
- Materials science
Background:
- Understanding magnetization dynamics in ferromagnets is crucial for spintronic devices.
- The Landau-Liftshitz-Gilbert (LLG) equation is a cornerstone for describing these dynamics.
- Dissipation mechanisms, such as spin relaxation and spin pumping, are key to controlling magnetic behavior.
Purpose of the Study:
- To investigate magnetization dynamics of a single domain ferromagnet using scattering theory.
- To derive the LLG equation and its parameters from first principles.
- To elucidate the contributions of bulk and interface effects to magnetic energy dissipation.
Main Methods:
- Employing scattering theory to model the interaction between the ferromagnet and a thermal bath.
- Expressing effective fields and the Gilbert damping tensor as functions of the scattering matrix.
- Analyzing energy currents generated by time-dependent magnetization.
Main Results:
- Successfully recovered the Landau-Liftshitz-Gilbert equation from scattering theory.
- Expressed effective fields and Gilbert damping tensor in terms of the scattering matrix.
- Identified separable bulk (spin-relaxation) and interface (spin-pumping) contributions to energy dissipation.
Conclusions:
- Scattering theory provides a robust framework for understanding magnetization dynamics and dissipation.
- The derived Gilbert damping tensor in linear response is consistent with the Kubo formalism.
- This work offers a microscopic foundation for the phenomenological LLG equation and its damping parameters.
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