Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 11: Ferroelectric Domain Walls I (joint session KFM/TT)

TT 11.5: Talk

Monday, March 12, 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.