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

Sources on interface magnetization and anisotropy in Fe/Cu multilayers have been investigated via thermal behavior using d.c. magnetization and ferromagnetic resonance techniques. The samples were prepared by d.c. sputtering resulting in equal thickness elemental layers ranging in modulation wavelength from 1-3 nm. The interface anisotropy remains nearly constant at 0.32 erg/cm exp 2 through the temperature range 4-300K, 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 T exp 3/2 behavior, but whereas the volume Fe coefficient matches the bulk value of 3.5x10 exp -6 K exp -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.