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El túnel cuántico y la interferencia de fase cuántica en un imán de una sola molécula [Mn(II) 2Mn(III) 2]
Lollita Lecren1, Wolfgang Wernsdorfer, Yang-Guang Li
1Centre de Recherche Paul Pascal, CNRS UPR-8641, 115 av. du Dr. Albert Schweitzer, 33600 Pessac, France.
Journal of the American Chemical Society
|August 11, 2005
Resumen
Este estudio sintetizó un nuevo complejo de manganeso, [Mn4 (((hmp) 6 (((H2O) 2 (((NO3) 2) (((NO3) 2.2.5H2O, que exhibe un comportamiento magnético de una sola molécula. El complejo muestra tanto la relajación térmicamente activada como la de túnel cuántico, con interacciones ferromagnéticas y un estado fundamental definido.
Área de la Ciencia:
- Coordinación Química de la Coordinación
- Magnetoquímica es la Magnetoquímica.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los imanes de una sola molécula (SMM) son moléculas que exhiben una lenta relajación magnética.
- Comprender las interacciones magnéticas dentro de los cúmulos polinucleares es clave para diseñar SMM.
- El desarrollo de SMM es crucial para el almacenamiento magnético avanzado y las aplicaciones de computación cuántica.
Objetivo del estudio:
- Para sintetizar y caracterizar un nuevo grupo de manganeso con propiedades potenciales de SMM.
- Para investigar las interacciones magnéticas y la dinámica de relajación del complejo sintetizado.
- Para explorar el túnel cuántico de la magnetización y su influencia en el comportamiento SMM.
Principales métodos:
- Síntesis del complejo [Mn4 ((hmp) 6 ((H2O) 2 ((NO3) 2) 3 ((NO3) 2.2.5H2O a través de una reacción que involucra 2-hidroximetilpiridina y nitrato de manganeso.
- Difracción de rayos X monocristalino para determinar la estructura cristalográfica y el entorno de coordinación de los iones Mn.
- Mediciones de susceptibilidad magnética DC y AC para sondear las interacciones magnéticas y los procesos de relajación.
- magnetometría mu-SQUID para investigar la magnetización dependiente del campo y las interacciones entre SMM.
Principales resultados:
- La estructura cristalina revela un núcleo doble-cuboidal [Mn4] con heptacoordinado Mn2+ y hexacoordinado Mn3+ iones.
- Se identificaron interacciones ferromagnéticas entre los pares Mn2+-Mn3+ y Mn3+-Mn3+, lo que condujo a un estado básico de S(T) = 9.
- El complejo exhibe un comportamiento magnético de una sola molécula con relajación activada térmicamente (ley de Arrhenius) y túnel cuántico de magnetización por debajo de 0,34 K.
- Las mediciones de interferencia de fase cuántica confirmaron el valor de D y proporcionaron parámetros para la anisotropía transversal y la división del túnel en el estado de tierra.
Conclusiones:
- El complejo [Mn4] sintetizado es un prometedor imán de una sola molécula.
- La interacción de las interacciones ferromagnéticas y los efectos cuánticos dicta las propiedades magnéticas observadas.
- Este estudio proporciona información sobre los principios de diseño para SMM de alto rendimiento.
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