Magnetic inhomogeneities in (YSmCa)3(GeFe)5O12 and their elimination by improved growth procedures

We have found that inhomogeneities in the growth direction are a very common occurrence in LPE films of (YSmCa)₃(GeFe)₅O₁₂. These inhomogeneities, which occur over a wide range of solution compositions and growth conditions, are not detected by the usual measurements of bubble parameters. However, they can be observed in the presence of an in-plane field using a technique which we describe. Experiments using this technique indicate that there is a thin (≤ 1 μm) layer at the film/substrate interface which has magnetic properties significantly different from the rest of the film. Special growth procedures which will avoid the formation of this “interface layer” are described in detail. Comparisons between films with and without this layer show, surprisingly, that there is no direct correlation between the coercivity and the presence of this layer. However, a correlation between coercivity and samarium concentration is observed when all other growth parameters are kept as constant as possible.