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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 13: Focus Session: (Multi-)Ferroic States III

KFM 13.6: Talk

Wednesday, March 20, 2024, 11:30–11:50, EMH 225

Charged twin domain walls in antiferroelectric-like K₃[Nb₃O₆(BO₃)₂] — •Ivan N. Ushakov¹, Kasper A. Hunnestad¹, Christoph Grams², Joachim Hemberger², Petra Becker², Ladislav Bohatý², Thomas M. Tybell¹, and Dennis Meier¹ — ¹Norwegian University of Science and Technology (NTNU), Trondheim, Norway — ²University of Cologne, Cologne, Germany

Antiferroelectric materials exhibit an anti-polar alignment of electric dipoles, giving rise to intriguing physical properties and functional behaviors. In this work, we apply different scanning probe microscopy techniques to image and investigate the domains and domain walls in K₃[Nb₃O₆(BO₃)₂], a ferroelectric with antiferroelectric-like structure and properties. Using piezoresponse force microscopy, we show that the domains exhibit a pronounced piezoresponse, consistent with the non-centrosymmetric crystal structure. At the nanoscale, a chevron-like pattern of twin domains develops, where the crystallographic structure changes by 120^∘ across the domain walls. Interestingly, we observe the formation of charged twin walls with distinctly different piezoelectric and electrostatic responses, arising from a small canted electric moment of the otherwise anti-polar arrangement of electric dipoles. Furthermore, the charged domain walls can be controlled by local electric fields. Our findings provide insight into novel types of ferroic domain walls with unusual mechanical and electronic properties.