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

Abstract

We present a study of the structural and chemical properties of the magnetic insulator NiFe 2 O 4 on conductive Nb-doped SrTiO 3 (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 NiFe 2 O 4 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 NiFe 2 O 4 thin films grow with high quality over a wide range of oxygen partial pressures. These optimized NiFe 2 O 4 /SrTiO 3 heterostructures are envisioned as efficient spin filter tunnel contacts for room temperature application.

Influence of structure and cation distribution on magnetic anisotropy and damping in Zn/Al doped nickel ferrites

“…Oh has a negative impact on the damping due to hopping [Fe 2+ → Fe 3+ + e−] [6,7]. Furthermore, a mixed state between the inverse and normal spinel crystal structure is apparent, as has been evidenced for thin-film nickel ferrites in earlier works [6,9,28].…”

Enhanced ferrimagnetism in auxeticNiFe2O4in the crossover to the ultrathin-film limit

“…It is in this pursuit that ferrite materials are envisioned as high-T c spin filters with the ultimate goal to realize efficient spin filtering for application at room temperature. For example, NiFe 2 O 4 shows ferrimagnetic ordering up to T C = 865 K [7] and grows epitaxially on Nb-doped SrTiO 3 (001) perovskite electrodes [8,9]. Its inverse spinel lattice of the type Fe 3+ [Ni 2+ Fe 3+ ]O 4 however, exhibits a high structural complexity: Ni 2+ - cations are situated on octahedrally (O h ) coordinated lattice sites, while Fe 3+ -cations are equally distributed across both tetrahedral (T d ) and O h sites (Fig.…”

Hard x-ray photoelectron spectroscopy of tunable oxide interfaces

“…Although NiFe 2 O 4 is expected to be insulating, the growth of NiFe 2 O 4 on SrTiO 3 introduces defects like dislocations or mosaicity due to the large lattice strain. 39,40 NiFe 2 O 4 , therefore, electrically acts as a semiconductor. In general, throughout the entire in operando HAXPES measurement process, the sample was electrically and chemically stable, as shown in Figs.…”