Structural ordering of laser-processed FePdCu thin alloy films

Abstract

The Cu/Fe/Pd multilayers were transformed into L10-ordered FePdCu alloy by pulsed laser annealing. The initial multilayers were irradiated with 1, 10, 100, and 1000 laser pulses with duration time of 10 ns and energy density of 235 mJ/cm2. The gradual change of the number of laser pulses allowed to investigate the structural and magnetic properties at early stages of the transformation and L10-ordering processes. The measurements were carried out using X-Ray Diffraction, SQUID magnetometry, and Magnetic Force Microscopy. We found that L10 FePdCu (111)-oriented nanograins are formed by ordering of the coherent domains present in the as-deposited multilayer. The irradiation does not change the vertical size of the (111) crystallites. The L10 (002)-oriented grains appear at the later stages of the transformation and their size increases with the number of applied laser pulses. Additionally, the laser annealing induces the magnetic ordering of the irradiated material, which was observed as an increase of the saturation magnetisation and the Curie temperature with the rising number of pulses. We also observed, that irradiation with 1000 pulses leads to the loss of order, which is reflected in the drop of the Curie temperature.