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Anisotropía magnética gigante de átomos de cobalto individuales y nanopartículas
P Gambardella1, S Rusponi, M Veronese
1Institut de Physique des Nanostructures, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland. pietro.gambardella@epfl.ch
Science (New York, N.Y.)
|May 17, 2003
Resumen
Los átomos libres adquieren una anisotropía magnética gigante en las superficies. Los átomos de cobalto en el platino exhiben una anisotropía magnética significativa debido a las interacciones del sustrato, que varían con el tamaño de las nanopartículas. Esta investigación ayuda a comprender la anisotropía magnética en partículas pequeñas.
Área de la Ciencia:
- Ciencias de la superficie Ciencias de la superficie.
- Física de la materia condensada Física de la materia condensada Física de la materia condensada Física de la materia condensada Física de la materia condensada
- El magnetismo atómico del magnetismo atómico.
Sus antecedentes:
- Los átomos libres poseen momentos magnéticos isotrópicos.
- El ordenamiento atómico en las superficies reduce la simetría.
- Las interacciones superficiales pueden alterar significativamente las propiedades magnéticas.
Objetivo del estudio:
- Para investigar el desarrollo de la energía de anisotropía magnética en átomos de cobalto individuales en una superficie de platino (111).
- Explorar la influencia de la coordinación atómica y el tamaño de las nanopartículas en la anisotropía magnética.
- Para confirmar las predicciones teóricas con respecto a la anisotropía magnética inducida por la superficie.
Principales métodos:
- Deposición de átomos de cobalto individuales en un sustrato de platino (111).
- Ensamblaje de nanopartículas de cobalto (hasta 40 átomos).
- Medición de la energía de anisotropía magnética y los momentos magnéticos orbitales.
Principales resultados:
- Los átomos de cobalto individuales en el platino (111) exhiben una energía de anisotropía magnética gigante de 9 meV / átomo.
- Esta anisotropía surge de los momentos orbitales no extinguidos (1,1 magnetones de Bohr) y el fuerte acoplamiento espín-órbita.
- La energía de anisotropía magnética es sensible a los cambios de coordinación de un solo átomo dentro de las nanopartículas de cobalto.
Conclusiones:
- La reducción de la simetría en las superficies induce una anisotropía magnética significativa en los átomos libres.
- Los átomos de cobalto en el platino demuestran un sistema modelo para el estudio del magnetismo superficial mejorado.
- Los hallazgos son cruciales para la comprensión del magnetismo en sistemas magnéticos de tamaño finito y dispositivos a nanoescala.
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