THEORY OF DOMAIN DYNAMICS IN FILM HEADS

We recently proposed a variational principle and derived general non-linear dynamical equations for coupled motions of domains and walls in inductive recording heads. In this report, we model the yoke region of the core with a set of parallel 180-degrees walls and domains. Boundary conditions simulate connections to the poletip and back gap. To calculate the small-amplitude dynamics, we fourier-transform the motion equations in time and one of the two spatial dimensions. Since we integrate in advance with respect to the other spatial dimension, the set of linear equations that the computer needs to solve has only one index. Our method is inherently more correct and, in the present linear application, more efficient than its predecessors. Illustrative solutions for an input pulse simulating the reading of an ideal transition show how the flux channel broadens with increasing pulse width, generally supporting previous conclusions.