Evidence of defect-induced ferromagnetism in ZnFe$_{2}$O$_{4}$ thin films

TL;DR

This study investigates how defects influence ferromagnetism in ZnFe₂O₄ thin films, revealing that low oxygen pressures induce iron site occupation changes that enhance magnetic properties at room temperature.

Contribution

It provides new insights into defect-induced ferromagnetism in ZnFe₂O₄ thin films through spectroscopic analysis of cation site occupancy and magnetic behavior.

Findings

Low oxygen pressure causes iron superoccupation of tetrahedral sites.

Defect-induced cation site changes lead to high room temperature magnetic moments.

Ordered magnetic phase observed without Zn²⁺ inversion.

Abstract

X-ray absorption near-edge and grazing incidence X-ray fluorescence spectroscopy are employed to investigate the electronic structure of ZnFe$_{2}$O$_{4}$ thin films. The spectroscopy techniques are used to determine the non-equilibrium cation site occupancy as a function of depth and oxygen pressure during deposition and its effects on the magnetic properties. It is found that low deposition pressures below 10$^{-3}$ mbar cause iron superoccupation of tetrahedral sites without Zn$^{2+}$ inversion, resulting in an ordered magnetic phase with high room temperature magnetic moment.