Domain-wall nanoelectronics is considered to be a new paradigm for non-volatile memory and logic technologies in which domain walls, rather than domains, serve as an active element. Especially interesting are charged domain walls in ferroelectric structures, which have subnanometre thicknesses and exhibit non-trivial electronic and transport properties that are useful for various nanoelectronics applications^1,2,3. The ability to deterministically create and manipulate charged domain walls is essential to realize their functional properties in electronic devices. Here we report a strategy for the controllable creation and manipulation of in-plane charged domain walls in BiFeO₃ ferroelectric films a few nanometres thick. By using an in situ biasing technique within a scanning transmission electron microscope, an unconventional layer-by-layer switching mechanism is detected in which ferroelectric domain growth occurs in the direction parallel to an applied electric field. Based on atomically resolved electron energy-loss spectroscopy, in situ charge mapping by in-line electron holography and theoretical calculations, we show that oxygen vacancies accumulating at the charged domain walls are responsible for the domain-wall stability and motion. Voltage control of the in-plane domain-wall position within a BiFeO₃ film gives rise to multiple non-volatile resistance states, thus demonstrating the key functional property of being a memristor a few unit cells thick. These results promote a better understanding of ferroelectric switching behaviour and provide a new strategy for creating unit-cell-scale devices.

畴壁纳米电子学被认为是非易失性存储器和逻辑技术的新范例，其中畴壁而不是域用作有源元件。特别有趣的是铁电结构中的带电畴壁，它具有亚纳米厚度并表现出非常重要的电子和传输特性，可用于各种纳米电子应用^1,2,3。确定性地创建和操纵带电畴壁的能力对于在电子设备中实现其功能特性至关重要。_{在这里，我们报告了一种在 BiFeO 3}中可控地创建和操纵面内带电畴壁的策略几纳米厚的铁电薄膜。通过在扫描透射电子显微镜中使用原位偏置技术，检测到非常规的逐层切换机制，其中铁电畴生长发生在平行于施加电场的方向。基于原子分辨电子能量损失光谱、在线电子全息照相的原位电荷映射和理论计算，我们表明在带电畴壁处积累的氧空位是畴壁稳定性和运动的原因。_{BiFeO 3}面内畴壁位置的电压控制薄膜产生多个非易失性电阻状态，从而证明了作为几个单元厚度的忆阻器的关键功能特性。这些结果促进了对铁电开关行为的更好理解，并为创建单元级器件提供了新策略。