Adjustable imprint fields in LiNbO3 domain wall memories

A ferroelectric LiNbO3 single-crystal memory can record nonvolatile “0” and “1” data through the creation and erasure of conducting domain walls between two parallel and antiparallel domains in nanometer-sized dimensions, and the storing data can be nondestructively read out through on/off currents in large ratios. However, the memory generally suffers from the reliability issue due to the presence of the polarization-dependent imprint effect. In this study, we fabricated a mesa-like memory cell in contact with two side electrodes at the film surface. Once one side electrode is extended over the surface of the mesa by 60–140 nm, the switched domain underlying the electrode cannot be erased during the formation of the head-to-head domain wall. Under this condition, the imprint field can be adjusted continuously through slow charge injection so that the ultimate domain switching hysteresis loop is symmetric. The injected charge is stable and cannot be erased as the memory operation time is far shorter than 0.1 s, providing an effective way to contradict the polarization-dependent imprint field in the memory.