INVESTIGATION OF DOMAIN-WALL FORMATION AND MOTION IN MAGNETIC MULTILAYERS

The magnetization-reversal processes in two electrodeposited [Co64Ni31 Cu5 2 nm/Cu](200) multilayers are investigated using an advanced magne to-optical indicator film (MOIF) technique together with SQUID and vec tor vibrating sample magnetometry. The non-magnetic Cu spacers are con gruent to 1 nm thick in one specimen leading to predominantly antiferr omagnetic exchange coupling between the ferromagnetic Co64Ni31Cu5 laye rs, and congruent to 3 nm in the other, with ferromagnetic coupling. T he hysteresis loop of the ferromagnetic multilayer is conventional, in dicating the stages of domain-wall formation, motion and saturation. N ucleation and movement of domain walls in different layers proceed in a partially uncorrelated manner, and are determined by defects near th e surface edge and inside of the multilayer. As a result, the front of the magnetization reversal has a staggered configuration. The antifer romagnetic multilayer has an atypical loop, first with one susceptibil ity, then a step to a new value, then another susceptibility, and with non-symmetrical behavior about the field axis. Narrow and non-stagger ed domain-wall images in antiferromagnetically coupled layers are obse rved. The MOIF technique is used to provide a portrait of the vertical component of the magnetostatic field intensity, helping to elucidate the spin-flip and/or spin-flop processes which are apparently responsi ble for the hysteresis behavior.