Anomalous remanence of granular CoCu

Magnetization and remanence data for Co(6 Angstrom)/Cu(14 Angstrom)x15 multilayers, evaporated at room temperature on a Si (111) substrate, and subsequently annealed under argon atmosphere at 250 degrees C for 1 hour, were obtained. The magnetization measurements show an easy direction parallel to the him. The experimentally obtained reduced in-plane de demagnetization remanence curve for the annealed sample and for field applied nearly perpendicular to the easy axis, has a very unusual behavior: a clear minimum in the remanence versus the field dependence is seen with amplitude much higher than 1. In the framework of the model presented here, this effect is explained as caused by a portion of the sample, having negative remanent magnetization.