Conroy Michele, Småbråten Didrik René, Ophus Colin, Shapovalov Konstantin, Ramasse Quentin M, Hunnestad Kasper Aas, Selbach Sverre M, Aschauer Ulrich, Moore Kalani, Gregg J Marty, Bangert Ursel, Stengel Massimiliano, Gruverman Alexei, Meier Dennis
Department of Materials, London Centre of Nanotechnology, Imperial Henry Royce Institute, Imperial College London, London, SW7 2AZ, UK.
Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, 7491, Norway.
Adv Mater. 2024 Sep;36(39):e2405150. doi: 10.1002/adma.202405150. Epub 2024 Aug 9.
Ferroelectric domain walls are a rich source of emergent electronic properties and unusual polar order. Recent studies show that the configuration of ferroelectric walls can go well beyond the conventional Ising-type structure. Néel-, Bloch-, and vortex-like polar patterns have been observed, displaying strong similarities with the spin textures at magnetic domain walls. Here, the discovery of antiferroelectric domain walls in the uniaxial ferroelectric PbGeO is reported. Highly mobile domain walls with an alternating displacement of Pb atoms are resolved, resulting in a cyclic 180° flip of dipole direction within the wall. Density functional theory calculations show that PbGeO is hyperferroelectric, allowing the system to overcome the depolarization fields that usually suppress the antiparallel ordering of dipoles along the longitudinal direction. Interestingly, the antiferroelectric walls observed under the electron beam are energetically more costly than basic head-to-head or tail-to-tail walls. The results suggest a new type of excited domain-wall state, expanding previous studies on ferroelectric domain walls into the realm of antiferroic phenomena.
铁电畴壁是涌现电子特性和异常极化序的丰富来源。最近的研究表明，铁电壁的构型可以远远超出传统的伊辛型结构。已观察到奈尔型、布洛赫型和涡旋型极化图案，与磁畴壁处的自旋纹理有很强的相似性。在此，报道了在单轴铁电体PbGeO中发现反铁电畴壁。解析出具有Pb原子交替位移的高迁移率畴壁，导致壁内偶极方向发生180°循环翻转。密度泛函理论计算表明，PbGeO是超铁电体，使系统能够克服通常抑制偶极沿纵向反平行排列的去极化场。有趣的是，在电子束下观察到的反铁电壁在能量上比基本的头对头或尾对尾壁更高。这些结果表明了一种新型的激发畴壁态，将先前关于铁电畴壁的研究扩展到反铁电现象领域。
