Magnetic, magneto-optic and switching properties of amorphous GdFeSn-alloys

Abstract

We have examined the magnetic and magneto-optic properties of amorphous (Gd <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.26</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.74</inf> ) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</inf> Sn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> alloys having perpendicular uniaxial anisotropy. Films were prepared by e-gun evaporation. Further interest was directed to the thermal stability and the switching properties of these films. From the temperature dependence of the saturation magnetization the compensation temperature is found to decrease strongly with increasing <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</tex> while the Curie temperature is less affected. The magneto-optic Faraday and Kerr rotation investigated in the temperature range 4.2K <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\leq T \leq T_{C}</tex> exhibit a considerable increase with increasing Sn-content. The temperature behavior can be interpreted in terms of the mean field analysis indicating a strong reduction of the exchange constants and a stronger localization of the iron spin. Upon annealing to 1100K in air the GdFeSn films show characteristic changes of magnetic and magneto-optic properties. The addition of Sn tends to improve the thermal stability. The heat distribution in the magnetic layer and the substrate were examined experimentally to understand the local reversal of magnetization during thermomagnetic switching.