PHENOMENOLOGY OF DELTA-M CURVES AND MAGNETIC-INTERACTIONS

The deltaM curve is defined as a normalized difference of the two principal remanent curves: the isothermal remanent curve M(r) and the dc demagnetization curve M(d). In general non-zero deltaM arises from complicated interaction phenomena in magnetic material. Recent application bas been to systems of interacting particulate assemblies and polycrystalline thin films. In this paper, a simple phenomenological model is introduced to characterize magnetic interactions. The net magnetic field includes the external field, plus a mean field as well as a second-order interaction field representing fluctuations. With this model, the deltaM curve and relative properties of media can be easily fitted to experimental data. Excellent agreement with experiment for tape as well as single- and double-layer thin film media is found.