Polarized neutron reflectivity studies on granular Co80Fe20/Al2O3 multilayers

Abstract

Polarized neutron reflectivity (PNR) studies have been performed on granular multilayers [Co80Fe20(t(n))/Al2O3 (3nm)](m). For a non-percolating superferromagnetic (SFM) sample (t(n) = 1.3 nm) no spin-flip (SF) scattering was observed, measured at various points of the hysteresis, confirming that the magnetization reversal is achieved merely by domain nucleation and growth. For a percolated sample (t(n) = 1.6 nm) an oscillating magnetization depth profile from FeCo layer to FeCo layer along the multilayer stack was observed around the coercive field. The competition between long-range dipolar, short-range Neel and external field interactions apparently give rise to such a modulated magnetization depth profile in these magnetic multilayers. (c) 2007 Elsevier B.V. All rights reserved