r(Mn)xFe3-xO4/ZnO复合薄膜的磁性和输运特性研究

Fully epitaxial all oxide heterostructures Cr(Mn)xFe3-xO4/ZnO were fabricated by reactive sputtering on c-Al2O3. The microstructure and chemical component of the films were systematically investigated by X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy. A Quantum Design physical property measurement system (PPMS) was introduced to investigate the transport properties of the samples. Structural analyses reveal that the Cr(Mn)xFe3-xO4 films have a spinel structure. The Cr(Mn)xFe3-xO4 and ZnO films on c-Al2O3 are fully epitaxial, where the epitaxial relationship is Cr(Mn)xFe3-xO4 (111)||ZnO(0002). X-ray photoelectron spectroscopy shows that γ-Fe2O3 is absent in the Cr(Mn)xFe3-xO4 films, and the valences of Cr atom and Mn atom are mainly +3 and +2, respectively. The transport mechanism across the Cr(Mn)xFe3-xO4/ZnO interface is thermal emission /diffusion at low temperatures. The Schottky barriers ΦB of the ZnO based heterostructures are 0.362 eV(Cr) and 0.360 eV(Mn), respectively. The spin polarization of Cr(Mn)xFe3-xO4 at 30 K is 56.3% (Cr) and 43.8%(Mn), respectively.