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Oxygen-vacancy-ordered brownmillerite oxides offer a reversible topotactic phase transition by significantly varying the oxygen stoichiometry of the material without losing its lattice framework. This phase transition leads to substantial changes in the physical and chemical properties of brownmillerite oxides, including electrical and ion conductivity, magnetic state, and oxygen diffusivity. In this study, the variations in the resistive switching mode of the epitaxial brownmillerite SrFeO2.5thin film in the device were studied by systematically controlling the oxygen concentration, which could be varied by changing the compliance current during the first electroforming step. Depending on the compliance current, the SrFeO2.5devices exhibited either low-power bipolar resistive switching or complementary resistive switching behaviors. A physical model based on the internal redistribution of oxygen ions between the interfaces with the top and the bottom electrodes was developed to explain the complementary resistive switching behavior. This model was experimentally validated using impedance spectroscopy. Finally, the gradual conductance variation in the brownmillerite SrFeO2.5thin films was exploited to realize synaptic learning.

We have probed the structural and magnetic properties of PrVO3(PVO) thin films grown on the (001)-, (110)-, and (111)-oriented SrTiO3(STO) substrates. By changing the substrate orientation, the film out-of-plane orientation can be tuned to [110], [100]/[010], and [011]/[311], with different in-plane crystallographic variants. Accommodation of these variants on the different substrates implies different strain states, which have direct influence on the magnetic properties of PVO films. The magnetic moment of PVO films radically enhances from 0.4 μB/f.u. for STO(001) to 2.3 μB/f.u. for STO(111). While films on the (001)-oriented STO substrate display out-of-plane anisotropy, an in-plane anisotropy is observed for films grown on the (110)- and (111)-oriented STO substrates. In addition, a strong uniaxial magnetic anisotropy is also extracted for a partially relaxed film on the (110)-oriented STO substrate. Such findings can help oxide community for the better understanding of magnetic anisotropy in vanadate thin films, a subject that still suffer from significant lack of scientific investigations.

Brush-shaped ZnO heteronanostructures were synthesized using a newly designed thermal-assisted pulsed laser deposition (T-PLD) system that combines the advantages of pulsed laser deposition (PLD) and a hot furnace system. Branched ZnO nanostructures were successfully grown onto CVD-grown backbone nanowires by T-PLD. Although ZnO growth at 300 °C resulted in core–shell structures, brush-shaped hierarchical nanostructures were formed at 500–600 °C. Materials properties were studied via photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations. The enhanced photocurrent of a SnO2–ZnO heterostructures device by irradiation with 365 nm wavelength ultraviolet (UV) light was also investigated by the current–voltage characteristics.

The transport properties of as-deposited and plasma-treated SrRuO3thin films grown on SrTiO3(001) substrates were investigated. The SrRuO3thin films were treated with two different kinds of plasma gases: O2and H2. The difference in the transport properties of the two plasma-treated SrRuO3films was explained by the different oxygen vacancy concentration, based on different values for the out-of-plane lattice constant. This oxygen vacancy was significantly reduced by recovery annealing under high oxygen pressure.