Dresden 2026 – scientific programme
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FM: Fachverband Funktionsmaterialien
FM 12: German-French Focus Session: Materials Research in Polar Oxides – From Domain Engineering to Photonic and Electronic Devices I
FM 12.6: Talk
Wednesday, March 11, 2026, 11:15–11:30, BEY/0138
Polar Discontinuities, Emergent Conductivity, and Critical Twist-Angle-Dependent Behaviour at Wafer-Bonded Ferroelectric Interfaces — Andrew Rodgers1, Kristina Holsgrove1, Conor McClusky1, Samuel Seddon2, Marty Gregg1, and •Lukas M. Eng2,3 — 1Centre for Quantum Materials and Technologies, School of Mathematics and Physics, Queen’s University Belfast, UK — 2Institut für Angewandte Physik (IAP)- Nöthnitzer Str. 61, 01187 Dresden — 3ct.qmat: Dresden-Würzburg Cluster of Excellence*EXC 2147, TU Dresden, Germany
Probing novel properties, arising from twisted interfaces, has traditionally relied on the stacking of exfoliated 2D materials and the spontaneous formation of van der Waals (vdW) bonds. So far, investigations involving intimate covalent or ionic bonds have not been a focus. Yet, we show here that an established technique, involving thermocompressional wafer bonding, works well for creating twisted non-vdW interfaces. We have successfully bonded z-cut lithium niobate single crystals to create ferroelectric oxide interfaces with strong polar discontinuities and have mapped the associated emergent interfacial conductivity. In some instances, a dramatic change in microstructure occurs, involving local dipolar switching. A twist-induced collapse in the capability of the system to effectively screen interfacial bound charge is implied. Importantly, this only occurs around specific moiré twist angles with sparse coincident lattices and associated short-range aperiodicity. In quasicrystals, aperiodicity is known to induce pseudo-bandgaps and we suspect a similar phenomenon here.
Keywords: Bonding; Conductive interfaces; LiNbO3