Effect of laser ablation parameters on the structure and properties of multicomponent magnetic films

Co- and Fe-based alloy films were deposited and studied as perspective materials for the development of fast magnetic sensors. Pulsed Laser ablation deposition (PLD) was used as an appropriate technique to fabricate thin films preserving the stoichiometry of the complex bulk materials. Co67Cr7Fe4Si8B14, Fe75Nb3Cu1Si12B9, Fe40Ni40B20 and FexNi1-x (x=22, 36, 50) amorphous ribbons and metallic foils were ablated to deposit 10 - 120 nm thick films onto oxidized Si wafers using a KrF (lambda = 248 nm) laser with 30 ns pulses at fluence from 2 to 7 Jcm(-2). The films were analyzed by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), Rutherford backscattering spectrometry (RBS), x ray diffraction (XRD) and reflectivity (XRR), and ferromagnetic resonance (FUR). The structural and magnetic characteristics of the films strongly depend on the laser fluence. Stoichiometry is well preserved at low laser fluences. At higher fluences lighter elements (S B) are partly lost. Unwanted crystallization of films is also observed at the high fluence. Magnetic characteristics are closely related to the corresponding source materials, unless the light elements are partly lost. When this happens, increased magnetization of film is observed. The relaxation process in films was characterized by FMR linewidth. They are typically very narrow (110 - 250 G) for Fe - based alloys, indicating low values of magnetization motion damping (down to 6.06 x 10(7) rad/s) and therefore pointing to a perspective use of these materials for fast sensors.