Formation of Fe₁₆N₂ by Nitrogen Ion Implantation into Iron Thin Films

Abstract

N2+ ion implantation has been made to the 200 nm thick iron films. The analysis of the X-ray diffraction patterns revealed that at the dose of 4.0×10¹⁶ (N₂/cm²), nearly 35%of cubic iron in the film was transformed to body-centered tetragonal FeN, with orientation of its c-axis perpendicular to the film plane. Saturation magnetization of the implanted film at R. T. increased 2.8%, which can be interpreted by presence of Fe₁₆N₂. The expected value of the saturation magnetization 4 πM₈. of Fe₁₆N₂ was calculated to be 23.5 kG. The nitrogen implantation also induced magnetic anisotropy perpendicular to the film plane.