Magneto-optical measurements of Co-Pt (111) multilayers

An automated magneto-optical Kerr effect (MOKE) magnetometer was used to measure polar Kerr rotation (θK) and ellipticity (εK) loops of (0.3 nm Co/x Pt)15 multilayers with x = 0.3 to 1.2 nm. For most samples studied, the hysteresis loops exhibit typical perpendicular magnetization characteristics. The loops have unit squareness, and the normalized behavior of θK and εK is identical. However, for two samples with composition near (0.3 nm Co/1.0 nm Pt)15, the θK and εK loops are no longer identical, and exhibit bimodal features. Using MOKE major hysteresis loops and first-order reversal curves, a plausible explanation for this behavior is presented. © 1999 Elsevier Science B.V. All rights reserved.