Evidence of defect-induced ferromagnetism in ZnFe$_{2}$O$_{4}$ thin   films
  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. 
C. E. Rodr\'iguez Torres, F. Golmar, M. Ziese, P. Esquinazi, and S. P.   Heluani
cond-mat.mtrl-sci