| Due to the abundant physical and chemical properties, such as photovoltaic, piezoelectric, acousto-optic, ferroelectricity, metal-insulatortransition, colossal magnetoresistance and electromagnetic effect. The perovskite oxides have been attracted much attention in the fields of modern electronic information. Recently, Alkaline perovskite oxides have an extraordinary capacity for application in several functions such as displays, piezoelectric devices, sensors, transducers, thermoelectric generators, nonlinear optics, and wireless communication.d0 magnetism of alkaline perovskite oxides interface has been garnered a great of attention. For example, In-doped CaZrO3 has high-temperature proton conductivity, For the d0 transition metal oxides, it was found that one can use the bulk electronic structure to predict the existence of surface in-gap states. Thus, the importance of the study about d0 magnetism in bulk is self-evident.As we all know that the microelectronics technology achievement of Si semiconductor and its heterogeneous interface influence the development of information science at last century. The reason why Si can be widely used is mainly that the largely benefited from the excellent characteristics of Si/SiO2 interface and People begin to realize the importance of interface. Today, most of the semiconductor materials reflect its function through the interface, such as laser, field effect tube, solar cells and so on. So it has become the inevitable trend of scientific research to study the physical and chemical properties of peroviskite oxide interface.We use first principles to calculation some problem in this paper:(1) We study the holes-induced d0 magnetism associated with oxygen vacancy (Vo) in CaTiO3 and CaZrO3 have been investigated. To obtain holes, the divalent calcium and tetravalent IVB-group ions are replaced respectively by the monovalent alkali, IB-group and trivalent ?-group ions. It is found that the Vo can enhance the magnetic moment of few acceptors-doped CaTiO3, whereas it can enhance the magnetic moment in most acceptor-doped CaZrO3 except for La doping. Mainly it is because the Vo gives a rise to no gap-states in CaTiO3 but generates gap-states in CaZrO3. Based on the similar effect of Vo on the band structure in XTiO3 or in XZrO3(X=Ca, Sr, Ba), we suggest that there exists similar effect of Vo on d0 magnetism in acceptor-doped alkaline titanium (zirconium) perovskites.(2)We study the electronic structure properties of SrTiO3/LaAlO3 heterogeneous interface along the (001), (110) and (111) directions.On the (001) direction, with the increase of thickness of LaAlO3, n-type TiO2/LaO interface shows the phase change process from insulation to metal,but it does not happen in p-type SrO/AlO2 interface. Which can well agree with the theory of "polarization disaster". At the same time, according to the explanation of scientists, the conductivity of n-type TiO2/LaO interface is due to the polarization discontinuous and fold. So according to the explanation, we can change the electronic property of p-type SrO/AlO2 interface by adding fold, and we found that the introduction of oxygen vacancy can add fold. So we study the properties of the p-type interface through introducing oxygen vacancy and found that the introduction of oxygen vacancy really can change the nature of the p-type interface. On the other hand, we study the property of interface along the (111) direction, and found it can well according with the theory of "polarization disaster", but for (110) direction, the interface characteristics is not consistent with the theory of "polarization disaster". We thought it maybe the influence of surface atom, so we study the influence of surface atom on three direction and found that the surface atom can really influent the properties of the interface. |
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