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Resistivity of Mixed-Phase Manganites
1National High Magnetic Field Lab and Department of Physics, Florida State University, Tallahassee, Florida 32306.
Physical Review Letters
|January 3, 2001
Summary
This study models manganite resistivity using a phase-separated resistor network. Percolation phenomena accurately predict experimental results, explaining the bad-metal state under magnetic fields.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Statistical Mechanics
Background:
- Manganites exhibit complex electrical resistivity (rho(dc)) behavior.
- Phase separation into metallic and insulating domains is a key characteristic.
Purpose of the Study:
- To model and understand the electrical resistivity of manganites.
- To investigate the role of percolation in resistivity changes.
- To explain the bad-metal state induced by magnetic fields.
Main Methods:
- Utilized a random resistor-network model.
- Incorporated phase separation between metallic and insulating domains.
- Employed quantum calculations and microscopic considerations.
- Analyzed percolation phenomena with varying chemical composition and temperature.
Main Results:
- The model accurately reproduces experimental resistivity data, especially during percolation.
- Ferromagnetic clusters are predicted to exist above the Curie temperature.
- Small magnetic fields significantly alter resistivity, inducing a bad-metal state.
Conclusions:
- The random resistor-network model effectively explains manganite resistivity.
- Percolation is crucial for understanding resistivity transitions.
- The existence of ferromagnetic clusters and their role in the bad-metal state is supported.
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