Field analysis for magnetic heads with eddy currents or complex permeability

A technique is presented that uses numerical methods to obtain the fields for heads with eddy currents (finite permeability and conductivity) and for heads with complex permeability. Calculated results show that the effect of high permeability overrides the influence of eddy currents on fringe fields, even for small skin depths. Inside the pole tips, however, the fields are strongly dependent upon skin depth. Another result of interest is that the fields become elliptically polarized at low values of permeability and small skin depths. Heads with complex permeability exhibit similar results.