Study on the structural and magnetic properties of e-beam evaporated Co thin films annealed in vacuum

The present paper investigates the effects of thermal annealing on the structural and magnetic properties of Co thin films. The films were prepared by using electron-beam evaporation method onto Si (100) wafers and annealed in vacuum at 200 degrees C, 300 degrees C and 400 degrees C. A combination of X-ray diffraction, Rutherford back -scattering spectrometry, X-ray photoelectron spectroscopy, transmission electron microscopy and energy -dispersive X-ray spectrometry were used to characterize structural properties and the composition of the films, while magnetic behavior was studied by magneto-optical Kerr effect measurements. It was found that as deposited Co layer show predominantly uniaxial magnetic anisotropy, while after annealing at 200 degrees C and 300 degrees C a strong influence of fourfold contribution is observed, which is assigned to the thermally induced HCP -> FCC phase transition. With further increase in annealing temperature of 400 degrees C the isotropic contribution becomes the main component of magnetization. Besides, a strong variation in coercive field with annealing temperature was observed, where the coercivity seems to depend closely on the crystallite size. The highest value of HC equals similar to 70 Oe and was found for the temperature of 400 degrees C, where also mixing at the interface has started and formation of CoSi was observed. (c) 2022 Elsevier B.V. All rights reserved.