A Mossbauer study of DyFe2, YFe2 and HoFe2 thin films and multilayers

We have performed room temperature Conversion Electron Mossbauer Spectroscopy (CEMS) on thin films and multilayers of DyFe2, YFe2 and HoFe2 under applied magnetic fields of 0 T and 0.25 T in plane. The samples were constructed by M.R. Wells and R.C.C. Ward using Molecular Beam Epitaxy on sapphire substrates giving single crystals with the [110] plane parallel to the surface. The samples produced and studied are: thin films of DyFe2, YFe2 and HoFe2; Multilayers Of DyFe2/YFe2 with respective layer thicknesses of 50 Angstrom/50 Angstrom, 40 Angstrom/20 Angstrom, 20 Angstrom/4o Angstrom and 20 Angstrom/20 Angstrom. In all spectra the fits obtained are different to those found in bulk samples: all the iron sites in the cubic Laves Phase unit cell are magnetically inequivalent and the spins on the iron atoms always have a component perpendicular to the layers. With a field of 0.25 T applied in the plane of the sample the iron spins in the YFe2 thin film are rotated into the plane by a large amount (8.5degrees) compared to only a minor change in the DyFe2 thin film (1degrees). In multilayer systems the iron atom spins in the YFe2 layers appear to be locked to those in the DyFe2 layers.