Spin Reorientation Transition in Amorphous FeBSi Thin Films Submitted to Thermal Treatments

Abstract

Magnetic thin films have been obtained by radio-frequency (RF) sputtering on Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> substrates from a Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">78</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sub> target. The samples, with thickness t varying from 25 to 300 nm, are amorphous; crystalline fraction develops only for t ges 300 nm. Static hysteresis loops have been measured at room temperature by means of an alternating gradient magnetometer. Samples having t >80 nm display a two-slope hysteresis loops: first steep magnetization jump followed by a linear behavior between remanence and saturation revealing the occurrence of a spin-reorientation transition (SRT). The magnetic field H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</sub> at which the saturation is reached is connected with the perpendicular anisotropy. Magnetic force microscopy has been performed on all samples, indicating that for t les80 nm the magnetization lies in the film plane, while for larger thickness, it is oriented perpendicularly to the film plane. In this work, SRT has been studied as a function of sample thickness and perpendicular anisotropy. In particular, the effect of furnace annealing on the transition from in-plane to out-of-plane configuration will be studied in details.