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Resistive memories based on the resistive switching effect have promising application in the ultimate nonvolatile data memory field. This brief review focuses on the resistive switching phenomena in the perovskite oxide heterostructures, which originate from the modulation of the interface properties due to the movement of the oxygen vacancies and the ferroelectric polarization. Many recent experiments have been carried out to demonstrate the role of the oxygen vacancies by controlling the content of the oxygen vacancies in the oxide heterostructures with plenty of oxygen vacancies. The important role of the ferroelectric polarization was also carefully confirmed by analyzing the relationship between the current–voltage and polarization–voltage loops in the ferroelectric oxide heterostructures. The physical mechanisms have been revealed based on the developed numerical model.

Mechanism of resistance switching in heterostructure Au/LaMnO₃/SrNb_0.01Ti_0.99O₃ was investigated. In Au/LaMnO₃/SrNb_0.01Ti_0.99O₃ devices the LaMnO₃ films were fabricated under various oxygen pressures. The content of the oxygen vacancies has a significant impact on the resistance switching performance. We propose that the resistance switching characteristics of Au/LaMnO₃/SrNb_0.01Ti_0.99O₃ arise from the modulation of the Au/LaMnO₃ Schottky barrier due to the change of the oxygen vacancy concentration at Au/LaMnO₃ interface under the external electric field. The effect of the oxygen vacancy concentration on the resistance switching is explained based on the self-consistent calculation. Both the experimental and numerical results confirm the important role of the oxygen vacancies in the resistance switching behavior.

Using the first-principles calculations, the holes-induced $d^0$ magnetism associated with oxygen vacancy $(V_{\mathrm{\text{O}}})$ in ${\mathrm{\text{CaTiO}}}_3$ and ${\mathrm{\text{CaZrO}}}_3$ has been investigated. To obtain holes, the divalent calcium and tetravalent IVB-group ions are replaced respectively by the monovalent alkali, IB-group and trivalent III-group ions. It is found that the $V_{\mathrm{\text{O}}}$ can enhance the magnetic moment of few acceptors-doped ${\mathrm{\text{CaTiO}}}_3$, whereas it enhances the magnetic moment in most acceptor-doped ${\mathrm{\text{CaZrO}}}_3$ except for La doping. Mainly, it is because the $V_{\mathrm{\text{O}}}$ gives rise to no gap-states in ${\mathrm{\text{CaTiO}}}_3$ but generates gap-states in ${\mathrm{\text{CaZrO}}}_3$. Based on the similar effect of $V_{\mathrm{\text{O}}}$ on the band structure in ${\mathrm{\text{XTiO}}}_3$ or in ${\mathrm{\text{XZrO}}}_3$ (X = Ca, Sr, Ba), we suggest that there exists a similar effect of $V_{\mathrm{\text{O}}}$ on $d^0$ magnetism in acceptor-doped alkaline titanium (zirconium) perovskites.

In this study, we investigate the thermodynamic properties of the Ba${}_x$K${}_{1-x}$BiO₃ (BKBO) superconductor in the under- (x = 0.5) and over-doped (x = 0.7) regime, within the framework of the Migdal–Eliashberg formalism. The analysis is conducted to verify that the electron–phonon pairing mechanism is responsible for the induction of the superconducting phase in the mentioned compound. In particular, we show that BKBO is characterized by the relatively high critical value of the Coulomb pseudopotential, which changes with doping level and does not follow the Morel–Anderson model. In what follows, the corresponding superconducting band gap size and related dimensionless ratio are estimated to increase with the doping, in agreement with the experimental predictions. Moreover, the effective mass of electrons is found to take on high values in the entire doping and temperature region. Finally, the characteristic dimensionless ratios for the superconducting band gap, the critical magnetic field and the specific heat for the superconducting state are predicted to exceed the limits set within the Bardeen–Cooper–Schrieffer theory, suggesting pivotal role of the strong-coupling and retardation effects in the analyzed compound. Presented results supplement our previous investigations and account for the strong-coupling phonon-mediated character of the superconducting phase in BKBO at any doping level.

The novel Ba/Nb co-doped (Ba_0.15Sr_0.85)(Nb_0.15Co_0.85)O_3–δ oxide was synthesized by the solid-state reaction method. The (Ba_0.15Sr_0.85)(Nb_0.15Co_0.85)O_3–δ oxide was studied by X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetry (TG). The results demonstrate that the structural stability of the Ba/Nb co-doped (Ba_0.15Sr_0.85)(Nb_0.15Co_0.85)O_3–δ was improved significantly compared to that of the Ba-doped SrCoO_3–δ, in which a phase transformation occurred during the heating process. The incorporation of Nb⁵⁺ in the SrCoO_3–δ-based oxides can significantly stabilize the neighboring oxygen octahedral, resulting in the improved stability of the (Ba_0.15Sr_0.85)(Nb_0.15Co_0.85)O_3–δ. The oxygen sorption properties of (Ba_0.15Sr_0.85)(Nb_0.15Co_0.85)O_3–δ between 300°C and 950°C in air were investigated, and a high sorption capacity of 9.45 mL O₂(STP)/g oxide was obtained.