Experimental Ferroelectric Energy Landscapes: Insights into the Origin of Negative Capacitance

The concept of a free energy landscape is vital in describing the physics of ferroelectrics. New experimental methods allow the extraction of such energy landscapes directly from pulsed electrical measurements. This enables the identification of regions of negative energy curvature as a negative capacitance state in the ferroelectric. Here we show, that ferroelectric Hf0.5Zr0.5O2films with thin dielectric interface layers exhibit two separate regions of negative capacitance in accordance with Landau theory, which provides new insights into the physics of ferroelectrics.