Dynamic Stabilization of Metastable States in Triple-well Ferroelectric Sn2 P2 S6.

Abstract

Polarization dynamics in ferroelectric materials is governed by the effective potential energy landscape of the order parameter. The unique aspect of ferroelectrics compared to many other transitions is the possibility of more than two potential wells; this prospect leads to complicated energy landscapes with new fundamental and functional properties. In this work, we reveal direct dynamic evidence of a triple-well potential in the metal thiophosphate Sn2 P2 S6 compound using multivariate scanning probe microscopy combined with theoretical simulations. Our key finding is that the metastable zero polarization state can be accessed through a gradual switching process and is surprisingly stabilized over a broad range of electric fields. Simulations confirm that the observed zero polarization state originates from a kinetic stabilization of the non-polar state of the triple well, as opposed to domain walls. Dynamically, the triple well of Sn2 P2 S6 becomes equivalent to antiferroelectric hysteresis loop. Therefore, this material combines the robust and well-defined domain structure of a proper ferroelectric with dynamic hysteresis loops present in an antiferroelectric state. Moreover, the triple-well also enhances mem-capacitive effects in Sn2 P2 S6 which are forbidden for ideal double-well ferroelectrics. These findings provide a path to tunable electronic elements for beyond binary high-density computing devices and neuromorphic circuits based on three thermodynamically stable ferroelectric states. This article is protected by copyright. All rights reserved.