Oscillatory interlayer magnetic coupling of sputtered Fe/Mo superlattices

Abstract

Sputtered Fe/Mo superlattices grown on sapphire exhibit an oscillatory magnetic coupling as a function of Mo thickness. Ferromagnetic Fe layers 25 Å thick couple across the nonmagnetic Mo layers ferro- or antiferromagnetically with a period of ∼11 Å Mo. Ferromagnetically aligned films show the anticipated trend in longitudinal Kerr-rotation values based on calculation, while the antiferromagnetically coupled films in zero field yield only weak Kerr signals due to their characteristically ‘‘pinched’’ hysteresis loops. The films are well ordered and exhibit up to seven low-angle, x-ray diffraction peaks, but have negative magnetoresistive anomalies that are only ≲2% at 4.2 K.