Sub-coercive and multi-level ferroelastic remnant states with resistive readout

Ferroelectric devices use their electric polarization ferroic order as the switching and storage physical quantity for memory applications. However, additional built-in physical quantities and memory paradigms are requested for applications. We propose here to take advantage of the multiferroic properties of ferroelectrics, using ferroelasticity to create a remnant strain, persisting after stressing the material by converse piezoelectricity means. While large electric fields are needed to switch the polarization, here writing occurs at subcoercive much lower field values, which can efficiently imprint multiple remnant strain states. A proof-of-principle cell, with the simplest and non-optimized resistance strain detection design, is shown here to exhibit 13-memory states of high reproducibility and reliability. The related advantages in lower power consumption and limited device fatigue make our approach relevant for applications.