Conducting traces of domain walls for multilevel data storage in a LiNbO

The continuous tunability in the number of conducting domain walls in low-dimensional ferroelectric devices has attracted extensive attention in modulating synaptic weights during biological learning processes. However, most of domain switching events in ferroelectric single crystals occur abruptly to form a single domain pattern that lacks the synaptic plasticity. Here we found multilevel data storage of conducting traces of domain walls after erasure within mesa-like cells fabricated at the surface of a LiNbO3 single-crystal film. In contrast, the domain walls that are previously conducting become insulating after thermal annealing at 500 °C for 1 h. The intrinsic physics is correlated with charge injection into the domain wall regions to compensate the domain boundary charge at high temperature that reduces domain nucleation energies in promoting multidomain formation.