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Jahn-Teller phonon anomaly and dynamic phase fluctuations in La0.7Ca0.3MnO3
J Zhang1, P Dai, J A Fernandez-Baca
1Department of Physics, Florida International University, Miami, Florida 33199, USA.
Physical Review Letters
|May 1, 2001
Summary
Anomalous damping of lattice excitations in La0.7Ca0.3MnO3 was observed with increasing temperature. This behavior, linked to dynamic phase segregation, provides evidence for local fluctuations in the ferromagnetic-metallic state.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Physics
Background:
- La0.7Ca0.3MnO3 exhibits complex phase transitions.
- Understanding lattice dynamics is crucial for elucidating its electronic properties.
Purpose of the Study:
- To investigate the temperature dependence of lattice excitations in La0.7Ca0.3MnO3.
- To understand the anomalous damping of optical phonons near the ferromagnetic transition.
Main Methods:
- Inelastic neutron scattering was employed to probe lattice dynamics.
- Temperature-dependent measurements were performed across the ferromagnetic-metallic phase.
Main Results:
- An optical Jahn-Teller phonon showed continuous, anomalous damping with increasing temperature.
- This phonon mode collapsed above the Curie temperature (Tc = 240 K).
Conclusions:
- The anomalous damping is attributed to dynamic phase segregation.
- Evidence for local fluctuations, possibly polaron or charge/orbital ordering, in the ferromagnetic-metallic state was found.