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Relajación magnética lenta en el campo cero en el complejo tetraédrico [Co(SPh) [4]2-2-
Joseph M Zadrozny1, Jeffrey R Long
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|December 7, 2011
Resumen
Los complejos de cobalto tetraédricos exhiben un comportamiento magnético de una sola molécula, mostrando relajación independiente de la temperatura a bajas temperaturas y comportamiento activado térmicamente a temperaturas más altas. Los estudios de dilución revelan que las interacciones intermoleculares median el túnel cuántico.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Ciencia de los materiales Ciencia de los materiales.
- La física cuántica es la física cuántica.
Sus antecedentes:
- Los imanes de molécula única (SMM) son cruciales para el desarrollo de almacenamiento de datos de alta densidad y computación cuántica.
- Comprender la dinámica de la relajación magnética y los factores que influyen en el comportamiento de SMM es esencial para su aplicación práctica.
- Los complejos de cobalto con entornos de coordinación tetraédricos son candidatos potenciales para los SMM debido a sus propiedades electrónicas.
Objetivo del estudio:
- Para investigar el comportamiento del imán de una sola molécula de la sal Ph(4)P(+) del complejo tetraédrico [Co(SPh)(4)](2-).
- Para dilucidar los mecanismos de relajación magnética, incluyendo la dependencia de la temperatura y el túnel cuántico.
- Determinar el papel de las interacciones intermoleculares en las propiedades magnéticas observadas.
Principales métodos:
- Síntesis y caracterización del complejo [Co(SPh) ((4))) ((2-).
- Ac mediciones de susceptibilidad magnética para sondear las propiedades magnéticas dinámicas.
- Estudios magnéticos de temperatura variable bajo campos magnéticos aplicados.
- Experimentos de dilución utilizando una matriz de complejo de zinc isomorfo.
Principales resultados:
- El complejo [Co(SPh)(4)](2-) exhibe un comportamiento de imán de una sola molécula con un estado fundamental de S = 3/2 y una división axial de campo cero (D = -70 cm(-1)).
- La relajación magnética es independiente de la temperatura a temperaturas muy bajas, lo que indica un túnel cuántico, y sigue el comportamiento de Arrhenius por encima de 2.5 K (U(eff) = 21(1) cm(-1), τ(0) = 1.0(3) × 10(-7) s).
- Los campos magnéticos aplicados (1 kOe) promueven el comportamiento de Arrhenius en un rango de temperatura más amplio.
- Los estudios de dilución sugieren que las interacciones dipolares intermoleculares median la vía de túnel cuántico a baja temperatura.
Conclusiones:
- El complejo [Co ((SPh) ((4))) ((2-) funciona como un imán de una sola molécula.
- El túnel cuántico es una vía de relajación significativa a bajas temperaturas, probablemente influenciada por las interacciones intermoleculares.
- Se necesitan más estudios sobre el diseño molecular para optimizar el rendimiento de SMM y suprimir el túnel para aplicaciones prácticas.
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