Thickness dependence of crystalline state in FeZrNbCuB thin films obtained by sputter deposition

Differential scanning calorimetry, hysteresis measurements, X-ray diffraction, Mössbauer spectroscopy and transversal Kerr effect have been used to study the thickness and temperature dependence of magnetic properties and crystalline state of Fe₈₄Zr_3.5Nb_3.5B₈Cu₁ (at.%) thin films. Results indicate that a decrease of the saturation magnetization with increasing film thickness can be ascribed to the presence of a crystalline α-Fe phase at the early stages of film growth, followed by the deposition of the amorphous alloy. Thinner films, which have a significant crystalline phase in the as-prepared state, display less prominent crystallization features, whereas thicker films, with a significant amorphous phase in the as-prepared state, are characterized by much more pronounced crystallization effects, that are confirmed by Mössbauer and Transversal Kerr Effect measurements. Progressive thinning of a film by means of sputter etching allows to reduce the amorphous component, leading to the expected increase of saturation magnetization as the thickness decreases.