Soft X-ray absorption spectroscopy studies of single crystalline Fe–Ni–O alloy thin films

Abstract

Soft X-ray absorption spectroscopy (XAS) studies at the transition metal L 2,3 edges are carried out on a series of Fe 1− x Ni x O y (0 ≤ x ≤ 1) thin films. The XAS measurements are sensitive to the electronic states and the structural symmetry of the sites of the absorbing atoms. This study is a continuation of the previous results and further identifies the cation distribution in Fe 1− x Ni x O y system as x varies from 0 to 1. Systematic spectral evolutions with Ni concentration are observed in the whole series. Our results indicate that the crystal structure of the films resembles that of the spinel Fe 3O 4 for x ≤ 0.5. Rocksalt NiO structure is observed for x ≤ 0.8. An intermediate state may exist for x-values between 0.5 and 0.8.