Structural and magnetic properties of amorphous and nanocrystalline CoFeSiB thin films

Abstract

We have studied the structural, magnetic, and transport properties of CoFeSiB films with various Co compositions. Here, we focus on two amorphous Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">74</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> and nanocrystalline Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">78</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> thin films. Our results show that the amorphous film is a typical soft magnetic material, while the nanocrystalline film has a large saturation field. We conjecture that in the nanocrystalline film, the super-paramagnetism of nanocrystalline phase or antiferromagnetic exchange at the boundary between the amorphous and nanocrystalline phases causes the large saturation field.