**Thomas Kämpfe 1,2,\*, Bo Wang 3, Alexander Haußmann 1, Long-Qing Chen <sup>3</sup> and Lukas M. Eng 1,\***


Received: 1 January 2020; Accepted: 26 May 2020; Published: 11 September 2020

**Abstract:** Ferroelectric domain wall conductance is a rapidly growing field. Thin-film lithium niobate, as in lithium niobate on insulators (LNOI), appears to be an ideal template, which is tuned by the inclination of the domain wall. Thus, the precise tuning of domain wall inclination with the applied voltage can be used in non-volatile memories, which store more than binary information. In this study, we present the realization of this concept for non-volatile memories. We obtain remarkably stable set voltages by the ferroelectric nature of the device as well as a very large increase in the conduction, by at least five orders of magnitude at room temperature. Furthermore, the device conductance can be reproducibly tuned over at least two orders of magnitude. The observed domain wall (DW) conductance tunability by the applied voltage can be correlated with phase-field simulated DW inclination evolution upon poling. Furthermore, evidence for polaron-based conduction is given.

**Keywords:** conducting domain walls; ferroelectric films; lithium niobate; lithium niobate-on-insulator; scanning probe microscopy; non-volatile memory
