Development of interface-induced out-of-plane magnetic anisotropy in Ni/Fe/Ni trilayers

The magnetic properties of trilayers Ni(1000 Angstrom)/Fe-57(x Angstrom)/Ni (200 Angstrom) grown by evaporation in ultra-high vacuum, have been investi gated using Mossbauer spectroscopy, magneto-optic Kerr vector-magnetometry, and magnetic force microscopy (MFM). The data measured from a sample with Fe thickness x = 6 Angstrom show the development of an out-of-plane anisotr opy that tends to align the magnetization of the Fe-57 at about 40 respect to the normal to the layer plane. For higher Fe-57 layer thickness the data indicate that the magnetization lies in the film plane. The magneto-optic measurements and the MFM images demonstrate also that when x = 6 Angstrom t he Fe-57 layer induces a reorientation of the magnetization of the Ni outer most layer from in-plane to out-of-plane. The results are interpreted as du e to anisotropy effects induced at the interface Fe/Ni and to the gamma --> alpha transition that takes place between 6 and 16 Angstrom. (C) 2001 Else vier Science B.V. All rights reserved.