Layer selectivity of visible magneto-optical Kerr effects in pseudo spin-valve NiFe/FeMn/Co films

We report an experimental observation of two strikingly contrasting hysteresis behaviors between the magneto-optical (MO) Kerr rotation theta (K) and the ellipticity epsilon (K) in pseudo spin- vlave NiFe/FeMn/Co films. One is likely to reproduce the typical magnetic hysteresis loop obtainable with vibrating sample magnetometry while the other one reproduces a similar loop of the magnetorestistance curve ill some cases. This contrasting behavior can be explained by the different sensitivities of theta (K) and epsilon (K) to the ferromagnetic NiFe and Co layers. Using a simple model, we determine the ratios of the Co to NiFe layer sensitivities for both signals, and they are far from unity: theta (Co)(K)/theta (NtF,)(K) = -1.4 and epsilon (Co)(K)/epsilon (KNiF,) = 8.5. This laver selectivity in visible MO effects may allow that anomaly of the remarkably contrasting loops observed in NiFe/FeMn/Co films to be understood, and may have valuable implications for the study of layered magnetic films having different constituents in the individual layers.