Berlin 2015 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 7: Focused Session on Ferroic Domain Walls II (DF with MA)

DF 7.5: Topical Talk

Dienstag, 17. März 2015, 11:20–11:50, EB 107

The electronic structure of longitudinal domain walls: a DFT perspective — •Gustav Bihlmayer, Kourosh Rahmanizadeh, Daniel Wortmann, and Stefan Blügel — Peter Grünberg Institut (PGI-1) & Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Whenever ferroelectric domains meet “head-on”, a local accumulation of charge and/or defects compensating this charge can arise. As there is no general atomistic picture of these charged domain walls (DWs), ab-initio studies are still rather scarce. Motivated by detailed transmission electron microscopy images of transversal and longitudinal DWs in PZT [1,2], we studied these walls in PbTiO₃ using density functional theory (DFT). We explore the possibility of introducing defects acting as electron-acceptors or -donors at the DWs, as well as the localization of electrons due to correlation effects at the Ti site and compare the DW profiles with experimental data. Our calculations allow to investigate the distribution of defects in the DWs as well as the electronic structure of the bands hosting the accumulated charges. We find that states with magnetic- charge- and orbital order allow to realize an insulating (or semiconducting) behavior even in charged DWs [3]. We further discuss spin-polarization effects in the electron gas forming at the DWs due to relativistic phenomena in charged 90^∘ walls.
C. L. Jia et al., Nature Mater. 7, 57 (2008). [2] Y. L. Tang et al., Sci. Rep. 4, 4115 (2014). [3] K. Rahmanizadeh et al., Phys. Rev. B 90, 115104 (2014). Financial support of the EU grant NMP3-LA-2010-246102 (IFOX) is gratefully acknowledged.