Dennis Meier
NTNU Norwegian University of Science and Technology, Trondheim, Norway
Ferroelectric domain walls are a paradigmatic example for the rich physics and application opportunities of topological defects. The research on ferroelectric domain walls has revolutionized the way we understand polar structures and triggered the development of conceptually new devices for nanotechnology.[1] Despite the immense research efforts, we have scratched only the tip of the iceberg. This is because the quasi-2D walls are embedded in 3D materials and, hence, inaccessible to standard nanoscale imaging techniques. From a theoretical point of view, it is clear that the walls within the bulk are not perfectly flat and just like in other 2D systems, such as graphene and transition-metal dichalcogenides, related corrugation phenomena are crucial for their electronic responses.
In my talk, I will discuss the importance of the 3D nanoscale structure for the emergent transport properties at ferroelectric domain walls. By combining tomographic microscopy techniques and finite element modelling, we revealed how electrical currents spread in the complex network of domain walls and topologically protected vortices in ferroelectric ErMnO3.[2] The results demonstrate the impact of curvature effects on the electrical currents in domain wall networks, giving an additional degree of freedom for their control. In addition, I will briefly introduce novel imaging approaches that allow for studying the interaction of domain walls with point defects in 3D with atomic scale resolution.[3] The results expand previous work on ferroelectric domain walls into the third dimension and reveal new opportunities for domain-wall based multi-level resistance control and unconventional computing.
References
[1] D. Meier and S. M. Selbach, Nature Rev. Mater. 7, 15 (2022)
[2] E. D. Roede, et al., Adv. Mater. 2202614 (2022)
[3] K. A. Hunnestad, et al., Nature Commun. in print (2022)