Energy-Efficient\nFerroelectric Domain Wall Memory\nwith Controlled Domain Switching Dynamics

Abstract

High\nreadout domain-wall currents in LiNbO₃ single-crystal\nnanodevices are attractive because of their application in a ferroelectric\ndomain wall random access memory (DWRAM) to drive a fast memory circuit.\nHowever, the wall current at a small read voltage would increase nonlinearly\nat a much higher write voltage, which could cause high energy consumption.\nHere, we resolved this problem by controlling the two-step domain\nforward growth within a ferroelectric mesa-like cell that was formed\nat the surface of an X-cut LiNbO₃ single crystal. The mesa-like\ncell contacts two side Pt/Ni electrodes that extend over the cell\nsurface by 90 nm for the generation of an in-plane inhomogeneous electric\nfield. The domain forward growth processes at first in the formation\nof an inclined charged 180° domain to span the in-plane electrode\ngap under a write voltage of 5 V in a large readout wall current,\nand then, the domain expands fully throughout the entire cell in the\nformation of a neutral 180° wall to reduce the wall current by\n10 times at a higher write voltage of 6 V. Meantime, the domain below\nthe mesa-like cell in an opposite orientation is unchanged to serve\nas the reference. A higher wall current at a lower read voltage and\na lower wall current at a higher write voltage can satisfy both requirements\nof low energy consumption and fast operation speeds for the DWRAM.