Discontinuous transitions in double-exchange materials
It is shown that the double-exchange Hamiltonian, with weak antiferromagnetic interactions, has a rich variety of first-order transitions between phases with different electronic densities and/or magnetizations. The paramagnetic-ferromagnetic transition moves towards lower temperatures, and becomes...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2001 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/60058 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/60058 |
| Access Level: | acceso abierto |
| Palabra clave: | 53 Inelastic-neutron-scattering Metal-insulator-transition Mixed-valence manganites Spectral moments method colossal-magnetoresistance Phase-separation Manganese perovskites Spin dynamics Ferromagnetic manganites Charge localization. Física (Física) Física-Modelos matemáticos 22 Física |
| Sumario: | It is shown that the double-exchange Hamiltonian, with weak antiferromagnetic interactions, has a rich variety of first-order transitions between phases with different electronic densities and/or magnetizations. The paramagnetic-ferromagnetic transition moves towards lower temperatures, and becomes discontinuous as the relative strength of the double-exchange mechanism and antiferromagnetic coupling is changed. This trend is consistent with the observed differences between compounds with the same nominal doping, such as La_(2/3)Sr_(1/3)MnO_(3) and La_(2/3)Ca_(1/3)MnO_(3). Our results suggest that, in the low doping regime, a simple magnetic mechanism suffices to explain the main features of the phase diagram. |
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