Physical Interpretation of Hysteresis Measurements through Numerical Simulation

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TauxeEAR-0229498Hysteresis measurements have become an important part of characterizing magnetic behavior of rocks in paleomagnetic studies. Theoretical interpretation is often difficult owing to the complexity of mineral magnetism and published data sets demonstrate remanence and coercivity behavior that is currently unexplained. In the last decade numerical micromagnetic modelling has been used to simulate magneticparticles. Such simulations reveal the existence of non-uniform remanent states between single and multi-domain, known as the "flower'' and "vortex'' configurations. These suggest plausible explanations for many hysteresis measurements yet fall short of explaining high saturation remanence, high coercivity data such as those commonly observed in fine grained submarine basalts. Micromagnetic modelling promises to provide plausible explanations for a wide range of hysteresis behavior. The investigators propose to extend their numerical simulations to a greater variety of shapes and sizes, including random assemblages of particles and shapes more complex than simple rods and cubes. They also will explore the parameter space of important magnetic materials other than room temperature magnetite. Finally, they will incorporate thermal fluctuations into their numerical code and expand the scope of modelling efforts to include this very important effect.