Scanning Electron Microscopy With Polarization Analysis (SEMPA)
M Scheinfein, John Unguris, Michael H. Kelley, Daniel T. Pierce, Robert Celotta
This was an extended abstract prepared for inclusion in the Microscopy & Microanalysis '99 Proceedings. It is a summary of Observation of Antiparallel Magnetic Order in Weakly Coupled Co/Cu Multilayers, which was published in Physical Review Letters, Vol. 82, No. 13, March 1999.Polarized neutron reflectivity and scanning electron microscopy with polarization analysis are combined to determine the magnetic structure of Co(6 nm)/Cu(6 nm) multilayers. These data resolve a controversy regarding the low-field state of giant-magnetoresistive (GMR) multilayers with weak coupling. As-prepared samples show a strong antiparallel correlation of in-plane ferromagnetic Co domains across the Cu. At the coercive field, the Co domains are uncorrelated. This irreversible transition explains the decrease in magnetoresistance from the as-prepared to the coercive state and indicates that the as-prepared state best represents the antiparallel configuration assumed in GMR analysis. For both states, the Co moments reside in domains with in-plane sizes of 0.5 m to 1.5 m.