Controlling the electronic structure of Co1-xFe2+xO4 thin films through iron doping

Article

关键词: X-RAY-ABSORPTION;    TRANSITION-METAL COMPOUNDS;    ELECTRICAL SPIN INJECTION;    MAGNETIC-ANISOTROPY;    VERWEY TRANSITION;    FE3O4;    ORIGIN;    DICHROISM;    PHOTOEMISSION;    SPINTRONICS;   

DOI  :  10.1103/PhysRevB.83.035121

来源: SCIE

【 摘 要 】

The electronic, magnetic and transport properties of iron-doped cobalt ferrite (Co1-xFe2+xO4) thin films grown epitaxially on MgO (001) substrates are investigated by soft x-ray absorption and photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, superconducting quantum interference device magnetometry, and resistivity measurements. The crystal structure for Co1-xFe2+xO4 is determined to be nearly inverse spinel, with the degree of inversion increasing for increased doping until it becomes fully inverse spinel for Fe3O4. The doped iron cations have a valency of 2+ and reside solely on octahedral sites, which allows for conduction owing to hopping between Fe2+ and Fe3+ octahedral cations. The addition of Fe2+ cations increases the electron density of states near the Fermi energy, shifting the Fermi level from 0.75 to 0 eV with respect to the top of the valence band, as the doping increases from x = 0.01 to 1. This change in electronic structure results in a change in resistivity by over two orders of magnitude. In contrast, the magnetic properties of CoFe2O4 thin films, characterized by a significantly reduced saturation magnetization compared to the bulk and large magnetic anisotropies, are affected less significantly by doping in the range from 0 to 0.63. These results show that Co1-xFe2+xO4 has tunable electronic properties while maintaining magnetic properties similar to CoFe2O4.

【 授权许可】

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