Lattice and superexchange effects in doped CMR manganites
نویسندگان
چکیده
منابع مشابه
Lattice and superexchange effects in doped CMRmanganites
We report on the influence of the lattice degrees of freedom on charge, orbital and spin correlations in colossal magnetoresistance (CMR) manganites. For the weakly doped compounds we demonstrate that the electron-phonon coupling promotes the trapping of charge carriers, the disappearance of the orbital polaron pattern and the breakdown of ferromagnetism at the CMR transition. The role of diffe...
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We investigate the stability of the charge exchange (CE) phase within a microscopic model which describes a single plane as in La0.5Sr1.5MnO4. The model includes Coulomb interactions (on-site and intersite), the Jahn-Teller term and the superexchange interactions due to eg and t2g electrons. By investigating the phase diagram at T = 0 in mean-field approximation we conclude that the superexchan...
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Previous theoretical investigations of colossal magnetoresistance (CMR) materials explain this effect using a "clustered" state with preformed ferromagnetic islands that rapidly align their moments with increasing external magnetic fields. While qualitatively successful, explicit calculations indicate drastically different typical resistivity values in two- and three-dimensional lattices, contr...
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We discuss the origin of the reentrant behaviors of insulating states above the Curie temperature of the colossal magnetoresistance manganites. We consider a system where charge ordering and ferromagnetism compete with each other. In the presence of randomness which pins charge order fluctuations, entropy-driven reentrant behaviors will appear, which explains the typical temperature dependence ...
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Low temperature resistivity of CMR manganites is investigated. At the ground state, conduction electrons are perfectly spin polarized, which is called half-metallic. From one-magnon scattering processes, it is discussed that the resistivity of a half metal as a function of temperature scales as ρ(T )− ρ(0) ∝ T . We take (Nd0.8Tb0.2)0.6Sr0.4MnO3 as an example to compare theory and experiments. T...
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ژورنال
عنوان ژورنال: Journal of Magnetism and Magnetic Materials
سال: 2004
ISSN: 0304-8853
DOI: 10.1016/j.jmmm.2003.11.089