On the Existence of Negative Capacitance: Examining Ferroelectric-Dielectric Stack Experiments Using the NLS and LK Models

The Landau–Khalatnikov (LK) model of ferroelectric switching includes an inherent region of negative capacitance (NC) in its lossless charge versus voltage description and allows the possibility of stabilization of the ferroelectric in this region to achieve quasi-static NC (QSNC). On the other hand, the nucleation-limited switching (NLS) model, which is another model used to describe ferroelectric switching, precludes QSNC and offers an alternative explanation for the appearance of an NC region in recent voltage-pulse experiments performed on ferroelectric-dielectric (FE-DE) stacks. As such, we investigate such experiments that probe the existence of an NC region using both the LK and NLS models. While the LK model can reproduce all experimental results seen in prior literature, we find that the NLS model is incapable of properly reproducing results under a multitude of investigation metrics. Hence, we conclude that the use of the NLS model to exclude the existence of QSNC is problematic.