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Project

Correlation between structural and magnetic properties in chemically disordered FePt thin films

The main objective of this project is to understand the correlation between the magnetic configuration of chemically disordered FePt thin films and the structural properties. The domain structure of FePt films depends strongly on the out of plane anisotropy (Kperp), film thickness, exchange constant and the saturation magnetization (Ms). Below a critical thickness (depending on thegrowing conditions) planar magnetic domains are found, while for larger thickness a stripe‐like magnetic structure forms.In order to obtain a phase diagram in critical thickness vs. the quality factor Q= Kperp/2Ms**2, we have grown a series of fifteen samples varying the film thickness and the Ar pressure in the sputtering chamber from 5 to 9 mTorr. By this procedure it is possible to maintain an almost constant crystalline texture, but relaxing the in‐plane stress. Previous measurements showed that stress is the predominant contribution in the perpendicular anisotropy. With an AFM‐MFM microscope, we have observed the transition from a striped pattern to in‐plane magnetic domains and we have also combined the image information with dc magnetization and ferromagnetic resonance (FMR) measurements at different microwave frequencies. We have already characterized the dynamical properties of FePt films in a limited set of samples obtaining the damping parameter from FMRlinewidths as a function of excitation frequency. Extending these measurements to the new set of samples will allow us to examine a dependence of damping with the fabrication conditions. FMR measurements at high frequencies (W‐band, f=95GHz) are extremely useful for the precise determination of the damping parameter.
Date:15 Jul 2014 →  30 Apr 2015
Keywords:EXPERIMENTAL STUDY, MAGNETIC MATERIALS, IRON PLATINUM, THIN FILMS
Disciplines:Condensed matter physics and nanophysics, Ceramic and glass materials, Materials science and engineering, Semiconductor materials, Other materials engineering