Magneto-Optical Investigation of Thin-Film Magnetic Structures

摘要

This study reports on the performance of a multilayer film structures which are very prospective material for the thin-film magnetic sensors. The magnetic and magnetooptical (MO) properties of NML/FM bilayers and also FM/NML/FM trilayers (with NML = Mo, Ta; FM = Fe, Co), prepared by using a magnetron sputtering system have been presented. FM layer thickness t_(P_e) and t_(C_o) in trilayers was variable from 25 to 100 A and the nonmagnetic layer (NML) thickness t_(NML) - from 5 to 50 A. In NML/FM samples the nonmagnetic layer thickness was variable from 5 to 1000 A. The measurements were performed on the magneto-optical magnetometer and by using of spectral technique. The dependencies of hysteresis characteristics (the saturation field and the coercivity) of Fe films on NML thickness were found. The dependence of the transverse Kerr effect (TKE) magnitude on t_(F_e) was established. It was shown experimentally that Kerr effect is sensitive to the magnetization up to a certain depth range below the surface of ferromagnetic - the information depth. It was discovered that the in-plane hysteresis characteristic of the trilayers are strongly dependent on t_(NML). So the existence of the exchange coupling between FM layers through NML and its oscillatory behavior (from antiferromagnetic (AF) to ferromagnetic (F) order) were experimentally established. It was found that period AF-F-AF oscillations of exchange coupling is equal to 6-8 A.