Abstract
(Multi-)ferroic materials attracted growing interest during the last decade due to their interesting (multiple)-ordering phenomena and the resulting applications (i.e. nonvolatile memories). Physical properties of boundaries are of particular importance as electronic device dimensions shrink and multiferroic bulk materials have not revealed a sufficient magneto-electric coupling so far. We will combine Density Functional calculations and microscopic techniques to examine basic properties of model boundaries, i.e. BiFeO3 71°/109°/180° domain walls (Fig. 1) and BaTiO3 90°/180° domain walls. The BaTiO3 180° domain wall is considered in the lower energetic parallel and in the higher energetic head-to-head configuration. The DFT calculations are performed within LDA+U on a plane wave basis set. PAW pseudopotentials have been incorporated to represent core states. Both, unit cell dimensions and ion positions have been relaxed to yield minimal energy structures. Transmission Electron Microscopy and in particular Electron Holography are applied to probe electric potential distributions and structure properties at the domain boundaries. Structural changes at the boundary occur due to lattice misfits and reconstruction of electronic orbitals. The thereby produced polarization change at the boundary leads to depolarization fields (Fig. 2). We particularly calculate and investigate such fields and discuss the prospects and problems of depolarization field measurements with TEM techniques. Moreover, the reconfiguration of the band structure at the boundary can lead to completely new physical properties like reduction of the band gap, magnetization change, etc [1, 2]. We calculate boundary band structures predicting ferromagnetic BiFeO3 71°/180° domain walls, band gap reduction, etc.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.