How pressure influences the magnetic properties of titanomagnetite and iron with implications for magnetic anomalies and core fields

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Pressure is an important variable in the Earth and planetary sciences, yet little is known abouthow extreme pressures influence the magnetic properties of geomaterials. Such knowledge isimportant to properly interpret magnetic anomalies and to understand how iron or iron alloys inthe solid inner core of planets interact with the magnetic fields generated in their outer cores. Wepropose to develop new high-pressure cell technology that allows us to directly measure the fullmagnetic vector of well-characterized samples as a function of pressure and temperature. Ourexperiments are intended to better understand pressure-induced changes in Curie temperatureand magnetic moment of relevant magnetic remanence carriers such as titanomagnetite andiron, including iron phases with Ni and S, with particular relevance to the cores of Earth, Marsand potentially Mercury. Numerical modelling will compliment the experiments by computingstructural and magnetic phase diagrams of iron and Fe-Ni/S alloys. The thermodynamicparameters will in part be fit to ab-initio phase diagram computations based on the clusterexpansion formalism. Magnetic ordering temperatures will be computed in the Fe and the Fe-Ni/S systems by evaluating Heisenberg Hamiltonians in the mean-field-approach and randomphase-approximation. Exchange interaction parameters for the Heisenberg Hamiltonians will beobtained by fitting ab-initio computations on magnetic structures.