Wide-Range Structural and Chemical Stability of the Magnetic Oxide NiFe2O4 Grown by O2-Assisted Pulsed Laser Deposition

We present a study of the structural and chemical properties of the magnetic insulator NiFe2O4 on conductive Nb-doped SrTiO3 (001) substrates. Special regard is given to the dependence of the thin film properties on the O-2: Ar ratio during pulsed laser deposition. Using stoichiometric NiFe2O4 target material and varying the O-2 partial pressure from 0% to 100%, we find a nonzero oxygen threshold for heteroepitaxial growth and a stoichiometric Fe:Ni cation distribution. Moreover, our study clearly demonstrates that NiFe2O4 thin films grow with high quality over a wide range of oxygen partial pressures. These optimized NiFe2O4/SrTiO3 heterostructures are envisioned as efficient spin filter tunnel contacts for room temperature application.