Multilayer systems magnetostatically coupled: Magnetization profile and local volume domain structure

Abstract

Micrometric trilayer ribbons have been prepared consisting of a melt-spun Co-base ultrasoft amorphous nucleus surrounded by two electroplated magnetically harder polycrystalline CoNi layers. A detailed study of the magnetostatic coupling between the two magnetic phases has been performed by analyzing the local low-field hysteresis loops of the soft phase under the remanent stray field of the harder layers. Due to the magnetostatic character of the interaction, the dimensions and configuration of the hard phase play a very important role in the bias field distribution modifying the susceptibility and the fractional volume of different magnetization regions inside the soft nucleus. A reversal magnetization model is proposed to understand the complex magnetostatic interaction in such composite trilayer ribbons. An important achievement of this work is the derived understanding of magnetic structure of the system along ribbon axis, by means of a local displaceable pick-up coil employed during the hysteresis loop measurements.