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Competir el magnetismo y la superconductividad en Na(x) CoO2 a medio dopaje
Manuel Bañobre-López1, Francisco Rivadulla, M Arturo López-Quintela
1Department of Physical Chemistry, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Journal of the American Chemical Society
|June 25, 2009
Resumen
La sustitución de sodio por hidrónio en Na{0.5}CoO{2} interrumpe las ondas magnéticas e induce la superconductividad. Este hallazgo sugiere que la superconductividad surge cerca de un estado específico de oxidación del cobalto, compitiendo con las fases magnéticas.
Área de la Ciencia:
- Química del estado sólido.
- Ciencia de los materiales Ciencia de los materiales.
- Física de la materia condensada Física de la materia condensada
Sus antecedentes:
- Los óxidos de cobalto de sodio (Na(x) CoO(2)) exhiben propiedades magnéticas y electrónicas complejas.
- El Na{x}CoO{2} semidopado se caracteriza por una fase magnética de onda de densidad de espín (SDW).
- La comprensión de los factores que controlan la superconductividad en los cobaltatos es crucial para el diseño de materiales.
Objetivo del estudio:
- Para investigar el impacto del intercambio iónico topotáctico en las propiedades electrónicas y magnéticas de Na{0.5}CoO{2).
- Explorar la relación entre el orden magnético y la superconductividad en este sistema.
- Para determinar la proximidad de la superconductividad a estados específicos de oxidación del cobalto.
Principales métodos:
- El intercambio iónico topotáctico de Na (((+) con H (((3) O (((+) en Na ((0.5) CoO ((2).
- Caracterización de los cambios estructurales, incluidas las modificaciones de la distancia entre capas.
- Análisis de los estados de oxidación del cobalto y sus propiedades magnéticas.
Principales resultados:
- La incorporación de iones de hidrónio mantuvo un estado constante de oxidación del cobalto.
- La distancia entre capas se incrementó significativamente con el reemplazo de H(3) O(+).
- Se observó una destrucción progresiva de la onda de densidad de espín.
- La superconductividad fue inducida con éxito en el material modificado.
Conclusiones:
- La sustitución topotáctica de Na{+} por H{3) O{+} puede suprimir el orden magnético e inducir la superconductividad en Na{0.5) CoO{2).
- La superconductividad en este sistema parece ocurrir más cerca de una relación Co3+/Co4+ de 1 que lo estimado previamente.
- El desarrollo de la superconductividad compite directamente con la formación de la fase magnética.
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