Sources of interface magnetization and interface anisotropy in Fe/Cu multilayers as revealed by thermal behavior

Abstract

Sources on interface magnetization and anisotropy in Fe/Cu multilayers have been investigated via thermal behavior using DC magnetization and ferromagnetic resonance techniques. The samples were prepared by DC sputtering resulting in equal thickness elemental layers ranging in modulation wavelength from 1 to 30 nm. The interface anisotropy remains nearly constant at 0.32 erg/cm2 through the temperature range 4-300 K, which is in stark contrast to large thermal effects observed in Ni-based systems, but is consistent with weak thermal variations of the crystal field in bulk Fe. Both the interface and volume Fe magnetizations follow Bloch T3/2 behavior, but whereas the volume Fe coefficient matches the bulk value of 3.5 × 10-6 K-3/2, the interface coefficient is 17 times greater. This indicates an interface Fe-Fe exchange which is much weaker than would be expected at a free Fe surface. © 1998 Elsevier Science B.V. All rights reserved.