Temperature dependence of magnetic anisotropy in a cylindrical Fe65Pd35 nanowire array

Abstract

Fe65Pd35 cylindrical nanowires (NWs) were synthesized in commercial anodic alumina porous templates via potentiostatic electrodeposition. The morphology, composition, and crystalline structure were analyzed by scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The NWs obtained are (10 ± 2) μm long and (200 ± 20) nm in diameter, with a polycrystalline microstructure. Magnetic properties were investigated by measuring the Zero Field Cooling-Field Cooling magnetization curves and hysteresis loops in the temperature range 10 K to 350 K. The magnetization easy axis is determined to be along the NWs axis, indicating strong anisotropy in this direction, which cannot be accounted for by only considering shape anisotropy. The hysteresis loops were fitted using the law of approach to saturation, obtaining the effective anisotropy field HA and the effective anisotropy constant Keff value for different temperatures. The blocking temperature TB dependence on the magnetic field H was also analyzed, indicating that a blocked magnetic contribution is present, arising from the smaller grains in the NWs. The observed enhancement in the effective magnetic anisotropy of the array throughout the studied temperature range is explained by considering magnetic interactions among these nanograins.