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The kinetics of the transformation from the disordered to the ordered phase has been studied in Fe56Pd44 thin films deposited on silicon substrates by Joule evaporation. Subsequent thermal treatments at 550 °C in vacuum were performed at different annealing times to promote the formation and the optimization of the ordered L10 FePd phase. X-ray diffraction allowed us to investigate the microstructure of the samples (grain size, volume fraction of the transformed phase, order parameter of the ordered phase, and average order of the alloy), whereas magnetic measurements allowed us to evaluate coercivity and to independently estimate the volume fraction of the ordered L10 phase. The kinetics of the transformation turned out to reach completion after 20 min of annealing time with the grain size growing with a power law with an exponent equal to 8.24. The resulting monophasic film has a high density of defects, which contribute to the magnetic coercivity. A linear relationship between the coercive field and the average order parameter of the alloy has been established. Finally, the evolution of the transformed phase obeys Avrami's law with an exponent of ∼0.4, indicating that the transformation is controlled by the nucleation mechanism without grain growth. [ABSTRACT FROM AUTHOR]

A novel nanofabrication technique based on self-assembling of polystyrene nanospheres and aimed to obtain magnetic nanodisks suspended in ethanol is here presented. Free-standing Ni80Fe20 disks having lateral dimension around 650 nm and thickness 30 nm were obtained by using nanosphere lithography on a sputtered continuous thin film. The multi-step nanofabrication process will be explained, in detail. The process end-product can be used as suitable magnetic carriers having nearly monodispersed size and simultaneously displaying high saturation magnetization and low-coercivity. Magnetisation reversal has been studied by room-temperature hysteresis loop measurements in either dot arrays attached on a substrate or in liquid-dispersed free-standing nanodisks. In both samples, the reversal is marked by magnetic vortex nucleation/annihilation. Such a behavior is confirmed for Ni80Fe20 dot arrays by measuring magnetic domain configuration, while numerical simulation is used for confirming magnetization reversal process in nanodisks. [ABSTRACT FROM AUTHOR]

We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself. [ABSTRACT FROM AUTHOR]

An annealing technique based on electrical current heating is extended from the case of metallic ribbons to thin films, by taking into account the role of thermal dissipation played by the film substrate. It has been employed in order to study the evolution of the magnetic properties with increasing annealing current intensity, and thus annealing temperature, of amorphous Fe-Co-Nb-Si-P-B thin films. Results are compared with conventionally annealed samples, treated in furnace at similar temperatures. Joule heating turns out to be more effective in softening the magnetic properties of the studied alloy in thin film form, with respect to furnace annealing. Additionally, Joule heating (performed at low current intensities) is able to promote the development of a spin reorientation transition in the studied film, which results in the appearance of a transcritical hysteresis loop and a dense stripe domain configuration. [ABSTRACT FROM AUTHOR]

Amorphous Fe73.9Nb3.1Cu0.9Si13.2B8.9 thin films have been produced by ion beam sputtering with two different beam energies (500 and 1000 eV). Magnetic measurements indicate that the samples display a uniaxial magnetic anisotropy, especially for samples prepared with the lower beam energy. Magnetization relaxation has been measured on both films with an alternating gradient force magnetometer and magneto-optical Kerr effect. Magnetization relaxation occurs on time scales of tens of seconds and can be described with a single stretched exponential function. Relaxation intensity turns out to be higher when measured along the easy magnetization axis. [ABSTRACT FROM AUTHOR]

The magnetic relaxation effects in [Fe.sub.73.9][Nb.sub.3.1][Cu.sub.0.9][Si.sub.13.2][B.sub.8.9] amorphous thin films produced by ion beam sputtering are analyzed by using different methods as a function of magnetic anisotropy. Magnetization relaxation has occurred on time scales of tens of seconds and relaxation intensity is found to be higher when measured along the easy magnetization axis.

The interplay between the structure and the magnetomechanical behavior of soft nanogranular CoFeAlO films with thickness ranging from 125 to 550 nm is analysed. The results indicate that due to the role of the mechanically stiff and insulating Al-O matrix, an increase if the resistivity leads to an increase of the anisotropy field and of the ferromagnetic resonance frequency.