Anisotropy and magnetostriction constants of nanostructured Fe50Co50 films

In this study Fe50Co50 films were grown using two different deposition systems: DC and RF sputtering. The DC system allowed substrate rotation during fabrication, and had the facility to heat the substrate up to temperatures above 1100 K. The RF system had stationary substrates and no substrate heating. The thickness range of the Fe50Co50 films was from 10 nm up to 100 nm. For each film, the anisotropy fields were determined from the magnetisation loops measured using a magneto-optic Kerr effect magnetometer to establish the symmetry of any anisotropy. Measurements were taken as a function of the direction of the magnetic field with respect to the film edge. It was found that the rotated films were isotropic in-plane, while the non-rotated films showed uniaxial anisotropy. The magnetostriction constants were measured using the Villari technique. X-ray diffraction (XRD) was used to determine the texture of the films, and the grain size was found using the Scherrer equation. It was determined that to achieve highly magnetostrictive Fe50Co50 films with uniform thickness, the films have to be rotated during growth at elevated temperatures.