Heterogeneous magnetism in Fe-doped bulk-amorphous and nanostructured Pd-basedalloys

Abstract

It has been shown in a previous work (Kapaklis et al 2005 J. Appl. Phys. 98 044319) that whereas the alloycomposition Pd40Cu30Ni10P20 can be easily cast as a bulk metallic glass, a partial replacement of Pd by Fe(Pd35Cu30Ni10Fe5P20) leads to a significant crystalline fraction under the same casting conditions. In order tounderstand the formation and properties of these precipitates, fully amorphous ribbons ofboth alloy compositions were also prepared by conventional melt-spinning. Magnetic datareveal that doping with 5 at.% iron leads to the formation of nanosized crystalline inclusionsin the residual bulk amorphous matrix which are completely absent in the ribbonmelt-spun from the same ingot. In both types of Fe-containing alloys the amorphous matrixcontains giant moments. Their size is of a few hundred (ingot) and a few tens (ribbon) ofBohr magnetons. The iron-free alloy corrected for the Langevin diamagnetism shows Pauliparamagnetism with similar susceptibility values in both the ingot and the ribbon.These values are close to the Pauli susceptibility of a control sample, a melt-spunPd82P18 alloy which is expected to be as homogeneous as the typical binary amorphous alloys. Thepossible origin of different, controversial magnetic behaviors reported in the literature forFe-doped Pd-based bulk and melt-spun alloys is discussed.