Recently,there is a surge of research interest in configurable ferroelectric conductive domain walls which have been considered as possible fundamental building blocks for future electronic devices.In this work,by using piezoresponse force microscopy and conductive atomic force microscopy,we demonstrated the controlled manipulation of various conductive domain walls in epitaxial BiFeO_(3) thin films,e.g.neutral domain walls(NDW)and charged domain walls(CDWs).More interestingly,a specific type of nanoscale domains was also identified,which are surrounded by highly conductive circular CWDs.Similar nano-scale domains can also be controlled created and erasured by applying local field via conductive probe,which allow nondestructive current readout of different domain states with a large on/off resistance ratio up to 102.The results indicate the potential to design and develop high-density non-volatile ferroelectric memories by utilizing these programable conductive nanoscale domain walls.
In this work,the resistive switching behaviors of ferroelectrictric BaTiO3/La0.67Sr0.33MnO3heterostructures deposited by pulsed laser deposition are investigated.The BaTiO3films show both well-established P–E hysteresis loops,and asymmetric reversible diode-like resistive switching behaviors,involving no forming process.It is found that both the ON/OFF ratio and the stability of resistive switching are substantially dependent on operation voltage(Vmax).At a Vmaxof15 V,a large ON/OFF resistance ratio above 1000 is obtained at a Vmaxof 15 V,which is able to maintain stability up to70-switching cycles.The above resistive switching behaviors can be understood by modulating interface Schottky barriers as demonstrated by I–V curve fitting.
The structural and magnetic properties of the Cu-doped ZnO(ZnO:Cu) under c-axis pressure were studied using first-principle calculations. It was found that the ZnO:Cu undergoes a structural transition from Wurtzite to Graphite-like structure at a c-axis pressure of 7–8 GPa. This is accompanied by an apparent loss of ferromagnetic stability, indicating a magnetic transformation from a ferromagnetic state to a paramagnetic-like state. Further studies revealed that the magnetic instability is closely related to the variation in crystalline field originated from the structural transition, which is in association with the overlapping of spin–charge density between the Cu2+ and adjacent O2-.
The electronic properties of TiO_2-terminated BaTiO_3(001) surface subjected to biaxial strain have been studied using first-principles calculations based on density functional theory. The Ti ions are always inward shifted either at compressive or tension strains, while the inward shift of the Ba ions occurs only for high compressive strain, implying an enhanced electric dipole moment in the case of high compressive strain. In particular, an insulator–metal transition is predicted at a compressive biaxial strain of 0.0475. These changes present a very interesting possibility for engineering the electronic properties of ferroelectric BaTiO_3(001) surface.
