A focused ion beam (FIB) methodology is developed to lift out suitable specimens containing charged domain walls in the improper ferroelectric ErMnO 3. The FIB procedure allows for extracting domain wall sections with well-defined charge states, enabling accurate studies of their intrinsic physical properties. Conductive atomic force microscopy (cAFM) measurements on a 700 nm thick lamella demonstrate enhanced electronic transport at charged domain walls consistent with previous bulk measurements. A correlation is shown between domain wall currents in cAFM and applied ion beam polishing parameters, providing a guideline for further optimization. These results open the door for the study and functionalization of individual domain walls in hexagonal manganites, an important step towards the development of atomic scale domain-wall devices that can operate at low energy.

Utilizing quantum effects in complex oxides, such as magnetism, multiferroicity and superconductivity, requires atomic-level control of the material`s structure and composition. In contrast, the continuous conductivity changes that enable artificial oxide-based synapses and multiconfigurational devices, are driven by redox reactions and domain reconfigurations, entailing longrange ionic migration and changes in stoichiometry or structure. While both concepts hold great technological potential, combined applications seem difficult due to the mutually exclusive requirements. Here, we demonstrate a route to overcome this limitation by controlling the conductivity in the functional oxide hexagonal Er(Mn,Ti)O3, by using conductive Atomic Force Microscopy (AFM) to generate electric-field induced anti-Frenkel defects, that is, charge-neutral anion interstitial-vacancy pairs. These defects are generated with nanoscale spatial precision, where they locally enhance electronic hopping conductivity by orders of magnitude without disturbing the ferroelectric order. We explain the non-volatile effects using density functional theory and discuss its universality, suggesting an alternative dimension to functional oxides and the development of multifunctional devices for next-generation nanotechnology.

Ferroelectric domain walls are quasi‐2D systems that show great promise for the development of nonvolatile memory, memristor technology, and electronic components with ultrasmall feature size. Electric fields, for example, can change the domain wall orientation relative to the spontaneous polarization and switch between resistive and conductive states, controlling the electrical current. Being embedded in a 3D material, however, the domain walls are not perfectly flat and can form networks, which leads to complex physical structures. In this work, the importance of the nanoscale structure for the emergent transport properties is demonstrated, studying electronic conduction in the 3D network of neutral and charged domain walls in ErMnO3. By combining tomographic microscopy techniques and finite element modeling, the contribution of domain walls within the bulk is clarified and the significance of curvature effects for the local conduction is shown down to the nanoscale. The findings provide insights into the propagation of electrical currents in domain wall networks, reveal additional degrees of freedom for their control, and provide quantitative guidelines for the design of domain‐wall‐based technology.

Focused ion beam (FIB) and scanning electron microscopy (SEM) are used to reversibly switch improper ferroelectric domains in the hexagonal manganite ErMnO3. Surface charging is achieved by local ion (positive charging) and electron (positive and negative charging) irradiation, which allows controlled polarization switching without the need for electrical contacts. Polarization cycling reveals that the domain walls tend to return to the equilibrium configuration obtained in the as-grown state. The response of sub-surface domains is studied by FIB cross-sectioning, enabling imaging in the direction perpendicular to the applied electric field. The results clarify how the polarization reversal in hexagonal manganites progresses at the level of domains, resolving both domain wall movements and the nucleation and growth of new domains. Our FIB-SEM based switching approach is applicable to all ferroelectrics where a sufficiently large electric field can be built up via surface charging, facilitating contact-free high-resolution studies of the domain and domain wall response to electric fields in 3D.