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Institut de minéralogie, de physique des matériaux et de cosmochimie

Mineralogy and magnetism with low dimensionality

The core activity of the team is the study of magnetism in nano-objects for which their low dimensionality (0D for nanoparticules, 1D for wires and 2D for surfaces) creates emerging physical and chemical properties.

The originality of our team is based on a use of magnetic spectroscopies that couples theoretical and experimental approaches and instrument development in a way that is unique. Our activity is divided into two areas that are very strongly interdisciplinary:

”Magnetic nanoparticules and paleomagnetism”: this research topic is at the intersection of Physics and Earth Sciences. Nanophases of magnetic minerals give major paleomagnetic information. In order to correctly interpret this information, however, we need to better understand the physico-chemical properties of these minerals as well as their relationship with geochemistry. These properties include biogenicity criteria for nanomagnetite crystals, origin of inverse thermoremanent magnetization in titanomagnetite, redox coefficient of mineral phases in primitive meteorites, and origin of magnetization in sediments. The magnetic phases studied are natural iron oxides or silicates, for which low dimensionality plays a crucial role in crystallographic, chemical and magnetic orders.

“Molecular magnetism”: this research topic lies at the intersection of Physics and Chemistry. Molecular magnets are molecules whose behaviour resembles that of classical magnets.  Because they are very small and perfectly monodisperse, original quantum phenomena such as relaxation by tunnel effect can arise. When these objects are deposited on surfaces, XMCD is the only method able to measure their magnetic properties. A large variety of these properties are thereby observed that depend on the nature of the molecules and their chemistry. The aim of our very low temperature XMCD measurements (300 mK) is to show the conservation of magnetic aisotropy that occurs with the appearance of crystallographic anisotropy.


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