Berlin 2018 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 2: Ferroelectric Domain Walls I (joint session KFM/TT)
KFM 2.10: Talk
Monday, March 12, 2018, 12:30–12:45, EMH 225
Unexpected BiFeO3 71 degree domain wall vibration — •Peng Chen and Sergey Artyukhin — Quantum Materials Theory, Istituto Italiano di Tecnologia, Genova (Italy)
Emergent phenomena excitations at domain walls are attracting enormous attention recently. Recent scanning impedance microscopy (SIM) measurements reveal AC conductance attributed to domain wall-localized phonons, that give important contributions to low-frequency dynamics in ferroic materials. In BiFeO3 the polarization change across 71 degree domain walls is perpendicular to the electric field applied by the SIM tip, and therefore the DW-localized phonon should not be excited by the tip. However, the experimental observations show a violation of this intuitive picture. Here we use Landau-Ginzburg theory and first-principles calculations to address this puzzling behavior.