Discovery of localized states of Fe 3d electrons in Fe16N2 and Fe8N films: an evidence of the existence of giant saturation magnetization

TL;DR

This study uses XAS and XMCD techniques to reveal localized Fe 3d electron states in Fe16N2 and Fe8N films, providing evidence for the origin of their giant saturation magnetization, which challenges existing theories.

Contribution

The paper presents the first experimental evidence of localized Fe 3d states in Fe16N2, explaining the giant saturation magnetization phenomenon.

Findings

Localized Fe 3d electron states observed

Polarization of N atoms detected

Hybridization between N and Fe atoms confirmed

Abstract

The mystery of giant saturation magnetization of Fe16N2 has remained for 37 years. In this letter, X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD) are used to study the electron states of Fe atoms in Fe16N2 and Fe8N films. Localized Fe 3d electron states, which are not expected from current theories (models), are observed. The XMCD spectra and elemental hysteresis loops reveal the polarization of N atoms and the hybridization of N and Fe atoms. This discovery points to the origin of giant saturation magnetization in Fe16N2.