Berlin 2018 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 2: Ferroelectric Domain Walls I (joint session KFM/TT)
KFM 2.5: Vortrag
Montag, 12. März 2018, 11:00–11:15, EMH 225
Interplay between point defects and domain wall mobility in improper ferroelectric YMnO3 — •Didrik René Småbråten, Dennis Meier, and Sverre Magnus Selbach — Norwegian University of Science and Technology (NTNU), Trondheim, Norway
Understanding the domain wall (DW) dynamics in ferroelectrics is key to controlling and fine-tune the domain structure and hence the ferroelectric properties. The DW dynamics strongly couple to the defect chemistry in the material, where stationary dopants may act as pinning centers or mobile defects may move with the DWs. The overall aim of this study is to give chemical guidelines for how to control the domain wall mobility via defect chemistry. Improper ferroelectric YMnO3 has a complex and exotic DW structure, including neutral, as well as positively and negatively charged DWs. Furthermore, the material has a large chemical flexibility being robust against donor and acceptor doping of its cation sublattices, and it is stable under both oxygen deficiency and excess. This unique flexibility makes YMnO3 an ideal model system for studying the interplay between DW mobility and defect chemistry. From density functional theory (DFT) calculations we show how changes in the two cation sublattices affect the DW mobility. In addition, we study how mobile anion defects couple to the DW movement and determine if they move with or pin the DWs.