Magnetostrictive hysteresis of TbCo/CoFe multilayers and magnetic domains

摘要

Magnetic and magnetostrictive hysteresis loops of TbCo/CoFe multilayers underfield applied along the hard magnetization axis are studied using vectorialmagnetization measurements, optical deflectometry and magneto optical Kerrmicroscopy. Even a very small angle misalignment between hard axis and magneticfield direction is shown to drastically change the shape of magnetization andmagnetostrictive torsion hysteresis loops. Two kinds of magnetic domains arerevealed during the magnetization: big regions with opposite rotation ofspontaneous magnetization vector and spontaneous magnetic domains which appearin a narrow field interval and provide an inversion of this rotation. We show that the details of the hysteresis loops of our exchange-coupledfilms can be described using the classical model of homogeneous magnetizationrotation of single uniaxial films and the configuration of observed domains.The understanding of these features is crucial for applications (for MEMS ormicroactuators) which benefit from the greatly enhanced sensitivity near thepoint of magnetic saturation at the transverse applied field.