Mössbauer study on Fe16N2 films prepared by ion-implant nitrification of iron films

Abstract

Mössbauer spectroscopy was carried out to elucidate the magnetic structure of Fe16N2 with the giant magnetization. Samples were prepared by ion-implant nitrification of single-crystal iron films, followed by an annealing at 150 °C for 60 h. The nitrification developed three Fe atom environments, attributable to three different Fe sites in Fe16N2 structure. The magnetic moments of the first, second, and third nitrogen neighbor Fe atoms were determined to be 1.3, 2.5, and 3.8 μB, respectively. The quadrupole effect in Fe16N2 was interpreted consistently on the basis of the consideration that the magnetization is directed along [001] and nitrogen atoms had a negative charge.