Anisotropic resistance switching in hexagonal manganites

The distribution and manipulation of oxygen defects, including oxygen vacancies (Ov) and interstitial oxygen (Oi), directly results in modifications in a variety of emergent functionalities in transition metal oxides. This is applicable in nanoscale control, which is a key issue in data and energy storage devices, such as resistive switching memory. Among all the oxygen-defect-related topics, nanoscale oxygen defect migration paths have a direct impact on the performance of memory devices, and are intrinsically determined by the structural anisotropy. Here, we use layered single-crystalline ferroelectric, hexagonal manganites (h-REMnO3) to demonstrate Oi-migration-induced nanoscale manipulation of conductance in the ab plane. Conversely, this unique phenomenon cannot be achieved along the c axis. Furthermore, a density functional theory calculation reveals that the energy barriers are lower for planar migrations of Oi, when compared to out-of-plane migration, and are responsible for such anisotropic resistance switching.