Calculating magnetic susceptibility over multiple length scales

DC power and radio frequency technology design can benefit from theories which predict magnetic permeability for a composite of nano-microscale magnetic particles in a magnetically neutral host. In this paper, composite permeability is calculated by connecting the microscale physics of the particles to the effective properties of the composite. At the microscale, numerical predictions are performed for a representative particle exposed to a magnetic field pulse. The simulation yields the particle's magnetic susceptibility, which is then generalized using magnetodynamics theory to obtain the susceptibility of a distribution of particles. The micro-magnetic study is extended to clusters of particles in order to study particle interactions. Effective medium theory is then used to describe the composite susceptibility of particles distributed in a neutral host.