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El ferromagnetismo de un nódulo de grafito del meteorito Canyon Diablo

J M D Coey¹, M Venkatesan, C B Fitzgerald

¹Physics Department, Trinity College, Dublin 2, Ireland. jcoey@tcd.ie

|November 15, 2002

Resumen

El grafito meteorítico exhibe un fuerte ferromagnetismo, con hallazgos que sugieren un efecto de proximidad magnética. Esta investigación explora el origen del magnetismo en los materiales de carbono más allá de las impurezas.

Área de la Ciencia:

Ciencia de los materiales Ciencia de los materiales.
Física del estado sólido Física del estado sólido
La geoquímica es la geoquímica.

Sus antecedentes:

Estudios recientes informan de un ferromagnetismo débil en el grafito y los materiales de carbono sintético.
Distinguir el ferromagnetismo intrínseco de los efectos de las impurezas en el carbono es un desafío debido a las señales débiles.

Objetivo del estudio:

Investigar el origen del ferromagnetismo en materiales grafíticos utilizando un nuevo enfoque experimental.
Determinar la contribución del grafito frente a las impurezas al magnetismo observado en muestras de meteoritos.

Principales métodos:

Análisis de diez muestras de grafito extraterrestre del meteorito Canyon Diablo.
Análisis de la composición de fase para cuantificar el contenido mineral y la magnetización.

Principales resultados:

Las muestras de grafito meteorítico mostraron un fuerte ferromagnetismo a temperatura ambiente.
Los minerales ricos en hierro (magnetita, kamacita) representaron aproximadamente dos tercios de la magnetización.
La magnetización restante, asociada con el grafito, indicó un promedio de 0,05 magnetones de Bohr por átomo de carbono.
La temperatura de ordenamiento magnético se observó cerca de 570 K.

Conclusiones:

El ferromagnetismo en el grafito meteorítico no se debe únicamente a las impurezas ricas en hierro.
Un efecto de proximidad magnética en la interfaz entre el grafito y las inclusiones minerales se propone como el mecanismo.
Este hallazgo ofrece información sobre el magnetismo en materiales carbonosos.

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