Investigation of structural, magnetic and electronic properties of FeTa films for varying Ta concentration at different annealing temperatures

Abstract

In the present work, temperature dependent magnetic, structural and electronic properties of FeTa films with increasing Ta concentration are investigated. X-ray reflectivity (XRR) studies reveal densification of the film with increasing Ta concentration. Thermal annealing also results in an increased electron density relative to as-deposited film, concurrent with increase in grain size as observed from X-ray diffraction (XRD) and results of Soft-X-ray absorption spectroscopy (SXAS). However, grain growth is inhibited with increasing Ta concentration by presence of Ta in grain boundary (GB) region. This also results in increase in magnetic coercivity (greater than150 %) as observed from magneto-optical Kerr effect (MOKE). The structural properties were further correlated with magnetic properties as observed from Polarized neutron reflectivity (PNR) and Ferromagnetic resonance (FMR). Effective magnetic moment of the samples, as observed from PNR decreases with increasing Ta concentration and increases with increasing annealing temperature, which is in agreement with FMR results. Scattering length density profiles, observed from simultaneous fitting of XRR and PNR show presence of an oxide layer at surface, as also confirmed from SXAS measurements.