Conducting Domain Walls in van der Waals Ferroelectric NbOI₂

In this study, using a set of scanning probe microscopy techniques, we investigate the electronic properties of the domain walls in the layered ferroelectric semiconductor of the transition metal oxide dihalide family, NbOI₂. Although the uniaxial ferroelectricity of NbOI₂ allows only 180° domain walls, the pristine 2D flakes, where polarization is aligned in-plane, typically exhibit a variety of as-grown domain patterns outlined by the electrically neutral and charged domain walls. The electrically biased probing tip can modify the as-grown domain structures. Piezoresponse force microscopy (PFM) domain imaging along with electrical measurements by conductive atomic force microscopy (C-AFM) reveals a conductive nature of the charged domain walls. It is shown that while modification of the pristine domain structure by the biased probing tip is possible, it is hampered by the high conductivity of the charged domain walls generated during the switching process.