Bias Voltage Dependence of the Magneto-Optical Effects of Rare Earth-Iron Amorphous Films

Abstract

It was found that GdTbFe films produced with a bias voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> ) of -40 V had a very large Kerr rotation angle (θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</sub> ). For V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> = -60 V, θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</sub> became extremely small and increased smoothly for V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> ≥ -70 V. The reflectivity (R) reached a maximum at -30 V and decreased beyond that point. This V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> dependence was much stronger in TbFeCo films than GdTbFe films. R spectra indicated that the electron structure of GdTbFe films was unaffected by V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> . In GdTbCo films, the columnar structure became finer as V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> increased. It was concluded that changes in R result from changes in the ratios of high-density and low-density sections of the columnar structure.