Magnetic properties of thin film and granular [formula omitted] as a function of size

Thin amorphous [formula omitted] layers are prepared by sputtering to understand the influence of the spacer layer A on magnetic properties in the DyFe thickness regime where size effects are also important. The spacer layer A in this work is either Ti or Ca and we compare to our earlier work involving a spacer layer of Mo. The [formula omitted] layer is amorphous and Mössbauer spectroscopy indicates that two types of Fe site are present. Finite size effects manifest themselves below a size of 10 nm in a reduction of magnetic ordering temperature [formula omitted] and coercivity [formula omitted] For equal values of d, the reduction of [formula omitted] and [formula omitted] is larger for the system with a Ti or Mo spacer layer as compared to the Ca spacer layer. We argue that both size and the structure of the interface are important in lowering [formula omitted] and [formula omitted] The temperature dependence of coercivity is also studied and suggests that magnetic reversal via domain wall movement occurs in our thinnest films.