High readout domain-wall currents in LiNbO 3 single-crystal nanodevices are attractive because of their application in a ferroelectric domain wall random access memory (DWRAM) to drive a fast memory circuit. However, the wall current at a small read voltage would increase nonlinearly at a much higher write voltage, which could cause high energy consumption. Here, we resolved this problem by controlling the two-step domain forward growth within a ferroelectric mesa-like cell that was formed at the surface of an X-cut LiNbO 3 single crystal. The mesa-like cell contacts two side Pt/Ni electrodes that extend over the cell surface by 90 nm for the generation of an in-plane inhomogeneous electric field. The domain forward growth processes at first in the formation of an inclined charged 180°domain to span the in-plane electrode gap under a write voltage of 5 V in a large readout wall current, and then, the domain expands fully throughout the entire cell in the formation of a neutral 180°wall to reduce the wall current by 10 times at a higher write voltage of 6 V. Meantime, the domain below the mesa-like cell in an opposite orientation is unchanged to serve as the reference. A higher wall current at a lower read voltage and a lower wall current at a higher write voltage can satisfy both requirements of low energy consumption and fast operation speeds for the DWRAM.

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The microampere-level domain wall currents in LiNbO3 single crystals have promising applications in nonvolatile ferroelectric domain wall random access memory and logic with high-density integration, ultrafast operation speeds, and almost unlimited switching cycles. For the memory commercialization, the improvements of the reliability and operation speed of the devices are challenging due to the high-field charge injection. The injected charge could compensate the domain-wall boundary charge that screens the domain switching field and reduces the domain wall current. In this work, two kinds of memory nanocells were fabricated on the surfaces of X-cut LiNbO3 single crystals to study the geometry-dependent charge injection. The striped memory cell due to the appearance of the size-driven reconstruction has a smaller coercive field than that of a clamped memory cell without relaxation of the lattice matching stress, which reduces low-frequency charge injection and increases the domain switching speed. At an operating voltage of 5 V, we observed a retention time of more than 1 week and an on/off current ratio of 2 × 104 for a striped-like cell, paving the route to integrate energy-efficient high-density domain wall memory in high reliability.