Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), 7034, Trondheim, Norway.
Experimental Physics V, University of Augsburg, 86159, Augsburg, Germany.
Nano Lett. 2021 Nov 24;21(22):9560-9566. doi: 10.1021/acs.nanolett.1c03182. Epub 2021 Nov 4.
The direct current (dc) conductivity and emergent functionalities at ferroelectric domain walls are closely linked to the local polarization charges. Depending on the charge state, the walls can exhibit unusual dc conduction ranging from insulating to metallic-like, which is leveraged in domain-wall-based memory, multilevel data storage, and synaptic devices. In contrast to the functional dc behaviors at charged walls, their response to alternating currents (ac) remains to be resolved. Here, we reveal ac characteristics at positively and negatively charged walls in ErMnO, distinctly different from the response of the surrounding domains. By combining voltage-dependent spectroscopic measurements on macroscopic and local scales, we demonstrate a pronounced nonlinear response at the electrode-wall junction, which correlates with the domain-wall charge state. The dependence on the ac drive voltage enables reversible switching between uni- and bipolar output signals, providing conceptually new opportunities for the application of charged walls as functional nanoelements in ac circuitry.
直流（dc）电导率和铁电畴壁的新兴功能与局部极化电荷密切相关。根据电荷状态，壁可以表现出不同寻常的直流导通，从绝缘到金属样，这在基于畴壁的存储器、多级数据存储和突触器件中得到了利用。与带电壁的功能直流行为相反，它们对交流电（ac）的响应仍有待解决。在这里，我们揭示了 ErMnO 中带正电荷和带负电荷的壁的 ac 特性，与周围畴的响应明显不同。通过结合宏观和局部尺度上的电压相关光谱测量，我们证明了在电极-壁结处存在明显的非线性响应，这与畴壁的电荷状态有关。对 ac 驱动电压的依赖性使得在单极和双极输出信号之间进行可逆切换成为可能，为将带电壁作为 ac 电路中的功能纳米元件的应用提供了概念上的新机会。
