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Phys. Rev. Lett. 98, 127202 (2007) [4 pages]

Competing Ferromagnetic and Charge-Ordered States in Models for Manganites: The Origin of the Colossal Magnetoresistance Effect

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Cengiz Şen1, Gonzalo Alvarez2, and Elbio Dagotto3,4
1National High Magnetic Field Laboratory and Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
2Computer Science & Mathematics Division and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
3Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 32831, USA
4Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA

Received 27 October 2006; published 21 March 2007

The one-orbital model for manganites with cooperative phonons and superexchange coupling JAF is investigated via large-scale Monte Carlo simulations. The results for two orbitals are also briefly discussed. Focusing on the electron density n=0.75, a regime of competition between ferromagnetic metallic and charge-ordered (CO) insulating states is identified. In the vicinity of the associated bicritical point, colossal magnetoresistance (CMR) effects are observed. The CMR is associated with the development of short-distance correlations among polarons, above the spin ordering temperatures, resembling the charge arrangement of the low-temperature CO state.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.98.127202
DOI:
10.1103/PhysRevLett.98.127202
PACS:
75.30.Mb, 75.10.Lp, 75.47.−m
 
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