The problem relevance is due to ability to use the investigation of the domain structure evolution with nanoscale charged walls under controlled highly non-equilibrium switching conditions using the modern experimental equipment with high spatial resolution represents the convenient model for studying the correlated metastable structure formation. The conductive charged domain walls (CDW) in ferroelectrics are very attractive for applications in nanoelectronics due to their nanometer sizes and ability to control the wall position by external electric field.
Domain walls are intrinsic to ferroelectric materials. Only recently thanks to transmission electron microscopy and atomic force microscopies (AFM, PFM, c-AFM) their real structure and electronic complexity have been revealed. Based on this the new paradigm of ferroic devices is now envisaged where the domain walls rather than the domains are the active elements. This field has been coined domain boundary engineering or domain wall nanoelectronics. The exploitation of the small domain walls width (of the order of a few nanometers) and their functional properties presents a high potential for industrial innovation with a new generation of devices with much higher storage density. Given the nanoscale size of the domain walls, advances in this field can only arise from investigations using state-of-the-art instrumentation in terms of spatial resolution.
CDW cannot be thermodynamically equilibrium due to additional depolarization energy nevertheless it exists in ferroelectrics along with the conventional equilibrium neutral domain walls. Metastable CDW not only appeared inevitably during polarization reversal in ferroelectric but can be absolutely stable for a long time thanks to the bulk screening of the depolarization fields. The long-range depolarization electric fields induced by bound charges at CDW result in ferroelectric-semiconductors to free charge accumulation in the vicinity of CDW and to considerable growth of conductivity. The external local electric field, created by the conductive tip of scanning probe microscope or by the system of micro-electrodes, allows to control the nucleation, annihilation, spatial position, velocity and concentration of nanometers-wide CDW. This fact opens the real opportunities for applications of conductive domain walls in nanoelectronics.