Improved electrical performance of LiNbO3 domain wall memories after thinning of interfacial layers at low temperatures

A nonvolatile ferroelectric LiNbO3 single-crystal memory utilizing erasable conducting domain walls inherits the advantages of commercial ferroelectric 1T1C/2T2C memories by avoiding destructive read operations. But its high-frequency domain switching hysteresis loop is typically asymmetric at room temperature, which can lead to retention issues. In this study, we show that this asymmetry is linked to the presence of interfacial layers near electrodes where the domains are volatile. During cooling of the device below 150 K, the loops become more symmetric when the interfacial domains become nonvolatile. The volatile-to-nonvolatile domain transition changes the domain switching mechanism and enables an energy-efficient non-superconducting cryogenic memory with improved operations.