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

An automated magneto-optical Kerr effect (MOKE) magnetometer was used to me asure polar Kerr rotation (theta(K)) and ellipticity (epsilon(K)) loops of (0.3 nm Co/x Pt)(15) multilayers with x = 0.3 to 1.2 nm. For most samples s tudied, the hysteresis loops exhibit typical perpendicular magnetization ch aracteristics. The loops have unit squareness, and the normalized behavior of theta(K) and epsilon(K) is identical. However, for two samples with comp osition near (0.3 nm Co/1.0 nm Pt)(15), the theta(K) and epsilon(K) loops a re no longer identical, and exhibit bimodal features. Using MOKE major hyst eresis loops and first-order reversal curves, a plausible explanation for t his behavior is presented. (C) 1999 Elsevier Science B.V. All rights reserv ed.