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Coercividad gigante en un imán unidimensional de coordinación de radicales de cobalto y radicales de cobalto
Norio Ishii1, Yoshitomo Okamura, Susumu Chiba
1Department of Applied Physics and Chemistry and Course of Coherent Optical Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan. ishi@pc.uec.ac.jp
Journal of the American Chemical Society
|December 14, 2007
Resumen
Un nuevo polímero radical metálico exhibe el campo coercitivo más alto jamás registrado, funcionando como un imán excepcionalmente duro a bajas temperaturas. Sin embargo, sus propiedades magnéticas pasan a ser suaves por encima de 10 K debido a los rápidos cambios de magnetización.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- El magnetismo es el magnetismo.
- Química de Polímeros La Química de Polímeros es la química de los polímeros.
Sus antecedentes:
- El desarrollo de materiales magnéticos avanzados es crucial para la innovación tecnológica.
- Los polímeros de radicales metálicos ofrecen propiedades magnéticas únicas debido a los espines de electrones no emparejados.
- Comprender la dependencia de temperatura del comportamiento magnético es clave para la aplicación de materiales.
Objetivo del estudio:
- Para sintetizar y caracterizar un nuevo polímero radical metálico.
- Para investigar las propiedades magnéticas, particularmente la coercitividad, del polímero sintetizado.
- Para explorar el comportamiento magnético dependiente de la temperatura y la dinámica de magnetización.
Principales métodos:
- Síntesis del polímero radical del cobalto (II) bis (hexafluoroacetilacetonato) bis (pyridyl) nitronilo-nitróxido ([Co (hfac) 2.BPNN]) y el cobalto (II) bis (hexafluoroacetilacetonato) bis (pyridyl) nitronyl-nitróxido ([Co (hfac) 2.BPNN]).
- Mediciones de propiedades magnéticas que incluyen bucles de histeresis para determinar el campo coercitivo.
- Estudios de susceptibilidad magnética y de magnetización dependientes de la temperatura.
Principales resultados:
- El polímero radical metálico [Co(hfac) 2.BPNN] demostró un campo coercitivo récord de 52 kOe (4.1 MA m-1) a 6 K.
- Esta excepcional coercitividad clasifica el material como el imán más duro reportado hasta la fecha.
- Por encima de 10 K, el material exhibió características magnéticas blandas atribuidas a la dinámica de reorientación de la magnetización rápida.
Conclusiones:
- El polímero metálico-radical sintetizado representa un avance significativo en los materiales magnéticos duros.
- La transición dependiente de la temperatura del magnetismo duro al suave resalta la naturaleza dinámica de su estado magnético.
- La investigación adicional sobre el control de la dinámica de magnetización podría conducir a nuevas aplicaciones en el almacenamiento magnético y la espintrónica.
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