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A través de la transición de reingreso estructural en BaFe2(PO4)2: influencia del ferromagnetismo bidimensional
Rénald David1, Alain Pautrat, Dmitry Filimonov
1Université Lille Nord de France, UCCS, UMR-CNRS 8181, ENSCL-USTL, Villeneuve d'Ascq, France.
Journal of the American Chemical Society
|August 24, 2013
Resumen
El fosfato de hierro de bario, BaFe2 ((PO4) 2), es el primer óxido ferromagnético de 2D Ising. Exhibe una transición estructural única de reentrada cerca de su temperatura de Curie, impulsada por el ordenamiento magnético y la inestabilidad de Jahn-Teller.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física del estado sólido Física del estado sólido
- El magnetismo es el magnetismo.
Sus antecedentes:
- Los materiales bidimensionales (2D) ofrecen propiedades físicas únicas debido a la dimensionalidad reducida.
- Los materiales de óxido con ordenamiento magnético son de gran interés para las aplicaciones espintrónicas.
- El ferromagnetismo aislado en óxidos es raro, lo que hace que los nuevos descubrimientos sean muy valiosos.
Objetivo del estudio:
- Para sintetizar y caracterizar BaFe2 (PO4) 2 como un nuevo óxido ferromagnético 2D Ising.
- Para investigar las transiciones de fase estructurales y magnéticas en BaFe2(PO4) 2.2.
- Comprender la interacción entre la estructura cristalina, la distorsión de Jahn-Teller y las propiedades magnéticas.
Principales métodos:
- Síntesis hidrotermal para la preparación de materiales.
- Difracción de rayos X para la determinación de la estructura cristalina.
- Espectroscopia de Mössbauer y Resonancia Paramagnética Electrónica (EPR) para la caracterización magnética.
- Cálculos de la Teoría Funcional de Densidad (DFT) para las estimaciones de energía.
Principales resultados:
- BaFe2(PO4)2 identificado como el primer óxido ferromagnético 2D Ising con capas de nido de abeja de FeO6 octaedros.
- Una transición estructural de trigonal a triclinica (P-1) ocurre por debajo de 140 K debido a la inestabilidad de Jahn-Teller.
- Una rara transición estructural de reentrada a trigonal (R-3) observada por debajo de ~70 K, coincidiendo con el ordenamiento ferromagnético (Tc = 65.5 K).
- La espectroscopia de Mössbauer reveló cambios discontinuos en la división cuadrupolar, que se correlacionan con la transición estructural.
- EPR confirmó la anisotropía magnética uniaxial y la presencia de dominios magnéticos por encima de Tc.
Conclusiones:
- BaFe2(PO4)2 exhibe una compleja interacción entre la distorsión de Jahn-Teller y el ferromagnetismo 2D Ising.
- La transición estructural de reentrada es un fenómeno único vinculado al ordenamiento magnético.
- Este material sirve como un sistema modelo para el estudio del magnetismo 2D Ising en óxidos.
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