Evolution of the electronic and lattice structure with carrier injection in BiFeO3

Article

关键词: DENSITY-FUNCTIONAL THEORY;    BISMUTH FERRITE;    DOPED BIFEO3;    FILMS;    NANOCRYSTALLINE;    CONDUCTION;    SYSTEMS;    OXIDE;   

DOI  :  10.1103/PhysRevB.93.174110

来源: SCIE

【 摘 要 】

We report a density-functional study on the evolution of the electronic and lattice structure in BiFeO3 with injected electrons and holes. First, the self-trapping of electrons and holes was investigated. We found that the injected electrons tend to be localized on Fe sites due to the local lattice expansion, the on-site Coulomb interaction of Fe 3d electrons, and the antiferromagnetic order in BiFeO3. The injected holes tend to be delocalized if the on-site Coulomb interaction of O2p is weak (in other words, U-O is small). Single-center polarons and multicenter polarons are formed with large and intermediate U-O, respectively. With intermediate U-O, multicenter polarons can be formed. We also studied the lattice distortion with the injection of carriers by assuming the delocalization of these carriers. We found that the ferroelectric off-centering of BiFeO3 increases with the concentration of the electrons injected and decreases with that of the holes injected. It was also found that a structural phase transition from R3c to the nonferroelectric Pbnm occurs, with the hole concentration over 8.7 x 10(19) cm(-3). The change of the off-centering is mainly due to the change of the lattice volume. The understanding of the carrier localization mechanism can help to optimize the functionality of ferroelectric diodes and the ferroelectric photovoltage devices, while the understanding of the evolution of the lattice with carriers can help tune the ferroelectric properties by the carriers in BiFeO3.

【 授权许可】

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