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Abstract
The need to tailor the magnetic properties of materials has become an important component of the growth of nanotechnology as new applications and devices require materials with specific magnetic behaviors. To achieve this goal, detailed structural and magnetic characterization must be done to determine the structural characteristics that cause these magnetic behaviors. Gd100-xFex nanostructures with x ≤ 40 were made by melt-spinning and inert-gas-condensation to investigate the role of disorder in the magnetic properties. X-ray diffraction (XRD), transmission electron microscopy (TEM) and extended x-ray absorption fine structure (EXAFS) reveal that the nanostructures are multi-phased consisting of hcp-Gd grains with amorphous Gd-Fe. EXAFS was also used to quantify the structural and chemical disorder. Magnetic measurements show the presence of a ferromagnetic transition near the bulk hcp-Gd transition corresponding to the presence of the hcp-Gd grains. Magnetic measurements also show a peak in the zero-field-cooled magnetization and a bifurcation of the zero-field-cooled and field-cooled magnetizations indicating a cluster-glass behavior. Samples containing Fe exhibit ferromagnetism above the observed Curie transition of the material as observed by non-zero coercivity above room temperature. Differences in the magnetic behaviors can be attributed to the differences in the disorder within the structures.
