Valence band structure and magnetic properties of Co-doped Fe3O4(100) films

Abstract

Structural and magnetic properties, and the valence band structure of pure and Co-doped (up to 33%) Fe3O4(100) films were investigated. Reconstruction of the Fe3O4(100) surface is found to be blocked by Co doping. Doped Co ions in Fe3O4 are in a charge state of 2 + and substitute the Fe2+ in the B site of Fe3O4. All the films exhibit room temperature ferromagnetism. Co doping changes the coercivity and reduces saturation magnetization. The density of states near the Fermi level is reduced by Co doping due to the decrease of Fe2+ in the B site, which might responsible for the decrease in conductivity and magnetoresistance of Co-doped Fe3O4. The Verwey transition in the range of 100–120 K is observed for the pure Fe3O4 film, while no transition could be detected for Co-doped Fe3O4 films.

Room Temperature CO Oxidation over Pt/MgFe2O4: A Stable Inverse Spinel Oxide Support for Preparing Highly Efficient Pt Catalyst

“…During the reaction process, a certain amount of Pt with positive value could decrease the adsorption strength of CO on the Pt sites and accelerate the reaction rate. , In the spectrum of Fe 2p, the Fe 2p 3/2 peak can be fitted into two bands located at about 710.7 and 712.4 eV. They can be ascribed to Fe o 3+ (Fe 3+ in octahedral sites) and Fe t 3+ (Fe 3+ in tetrahedral sites), respectively. − Almost all Fe species present with the value of +3. , The contributions of Fe o 3+ and Fe t 3+ were calculated to be 51.6% and 48.4%, respectively. As for the spectrum of Mg 2p, Mg 2+ ions located at both octahedral sites (Mg o 2+ ) and tetrahedral sites (Mg t 2+ ) were detected. ,, The contribution of Mg o 2+ and Mg t 2+ is presented by the constant Mg o 2+ /Mg t 2+ ratio of 1.72.…”

Hydrothermal synthesis and structure evolution of metal-doped magnesium ferrite from saprolite laterite

“…11(B)-(D). In the Fe 2p spectra of the ferrites, there were two nonequivalent Fe 2p 3/2 peaks at $710.73 eV, consistent with Fe B 3+ ions in octahedral sites and at $712.43 eV, consistent with Fe A 3+ ions in tetrahedral sites, [23][24][25] accompanied by satellite lines at $714.62 and $719.5 eV, indicating only the presence of Fe 3+ cations. 26 However, the contributions at $724.32 and $726.13 eV were assigned to the chemical state Fe 3+ of Fe 2p 1/2 .…”

Co on Fe3O4(001): Towards precise control of surface properties

“…This chemical flexibility is the reason for the wide variety of properties that they present, and its control enables to obtain engineered functionalities. A classic example is the family of Co-Fe spinel oxides, [2][3][4] spanning from the iron-only inverse spinel (Fe 3 O 4 ), a presumed half-metal ferrimagnetic conductor with a high Curie temperature of 850 K, 5 to the cobalt-only direct spinel (Co 3 O 4 ), an antiferromagnetic insulator. 6 One particular mixed oxide, CoFe 2 O 4 , has the highest magnetocrystalline anisotropy of all iron-containing spinels.…”