Synthesis of iron-nitride films by means of ion beam deposition

Abstract

Thin films of various iron nitride compounds have been deposited by using the ion beam deposition system with a new sputtering type of ion source and the dependence of their crystal structure and magnetic properties on preparation conditions has been investigated. Crystal structure and magnetic properties of the films depend significantly not only on substrate temperature Ts and nitrogen partial pressure P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N2</inf> but also on the arrival energy of the depositing ions. The films of multi phase, of α-Fe, γ'-Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> N and a unknown phase, with large saturation magnetization 4πMs about 24 kG are obtained by adjusting Ts, P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N2</inf> and the ion accelerating voltage Vp at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">200\sim250\deg</tex> C, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.5\sim2.0\times10^{-5}</tex> Torr and 20 V, respectively. Coercive force Hc of the films with large 4πMs decreases against an increase of 4πMs and is rather low about 1 Oe. These results indicate that the iron nitride films with large saturation magnetization and low coercive force deposited by the ion beam deposition system could be used in a thin film type of magnetic head for high density recording.