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Berry-phase effect in anomalous thermoelectric transport
Di Xiao1, Yugui Yao, Zhong Fang
1Department of Physics, The University of Texas, Austin, 78712, USA.
Physical Review Letters
|August 16, 2006
Summary
We present a theory explaining anomalous transport in ferromagnets using statistical forces. This work shows charge Hall current originates from Berry-phase corrections to orbital magnetization, not anomalous velocity.
Area of Science:
- Condensed matter physics
- Spintronics
- Transport phenomena
Background:
- Anomalous transport in ferromagnets is crucial for spintronic devices.
- Understanding the origins of charge Hall current under statistical forces is an ongoing challenge.
- Existing theories often rely on mechanical forces, limiting applicability to statistical driving forces.
Purpose of the Study:
- To develop a theoretical framework for the Berry-phase effect in anomalous transport driven by statistical forces.
- To elucidate the role of Berry-phase corrections to orbital magnetization in generating charge Hall currents.
- To establish fundamental relations between thermoelectric transport coefficients in ferromagnets.
Main Methods:
- Development of a finite-temperature theory for orbital magnetization.
- Derivation of explicit expressions for off-diagonal thermoelectric conductivity.
- Application of first-principles calculations to a specific material (CuCr(2)Se(4-x)Br(x)).
Main Results:
- A novel mechanism for charge Hall current generation via Berry-phase correction to orbital magnetization is proposed.
- Explicit formulas for off-diagonal thermoelectric conductivity are derived.
- The Mott relation between anomalous Nernst and Hall effects, and Onsager relations are confirmed.
- Quantitative agreement with experimental data for CuCr(2)Se(4-x)Br(x) is achieved.
Conclusions:
- The Berry-phase effect provides a unified explanation for anomalous transport in ferromagnets under statistical forces.
- The developed theory accurately predicts thermoelectric transport coefficients.
- This work offers a new perspective on designing and understanding spintronic and thermoelectric materials.
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