Magnetic properties and microstructure of thin-film media

The effects of microstructural disorder in the micromagnetic modelling of thin films are studied. Large-scale effects are studied using a model comprising spherical grains with short-ranged (liquid-like) order. It is shown that the microstructural disorder in exchange-coupled systems reduces the scale of feature sizes whilst retaining the positive delta Iota values characteristic of the effects of exchange coupling, A more realistic model of the microstructure using a Voronoi construction is also investigated. The results demonstrate the importance of non-uniform magnetisation states which necessitate a discretisation at the sub-grain level. An adaptive meshing finite element method is developed which predicts improved micromagnetic states at high resolution.