(MICROMAGN) Magnetism and microstructure: from the nanometre to the planetary scale.

Small particles of magnetic minerals in naturally occurring rocks are able to store information about how the Earth's magnetic field has changed throughout history, over geological timescales. This property results from the sizes, shapes and spacings of the magnetic particles within the minerals. In nature, particles of magnetite with diameters of 100-200 nm are the most efficient carriers of magnetic information. Particles of this size can be formed by the subdivision of much larger particles into a 'microstructure' that consists of a three-dimensional arrangement of small magnetic particles separated by non-magnetic material. The details of such microstructures have a fundamental effect on how different minerals store magnetic information. The proposed research project will use experimental electron microscopy techniques to measure the magnetic properties of several mineral samples. The aim of the work is to understand the relationship between the magnetic properties of the minerals at the nanometre length scale and the macroscopic magnetic properties of the Earth and other planets.