Transient negative differential capacitance, the dynamic reversal of transient capacitance in an electrical circuit, is of highly technological and scientific interest since it probes the foundation of ferroelectricity. We study a resistor-ferroelectric capacitor ($R$-FEC) network through a series of coupled equations based on Kirchhoff’s law, electrostatics, and Landau theory. We show that transient negative capacitance (NC) in a $R$-FEC circuit originates from the mismatch in switching rate between the free charge on the metal plate and the bound charge in a ferroelectric (FE) capacitor during the polarization switching. This transient free charge–polarization mismatch is driven by the negative curvature of the FE free-energy landscape, and it is also analytically shown that a free-energy profile with a negative curvature is the only physical system that can describe transient NC in a $R$-FEC circuit. Furthermore, transient NC induced by the free charge–polarization mismatch is justified by its dependence on both external resistance and the intrinsic FE viscosity coefficient. The depolarization effect on FE capacitors emphasizes the importance of negative curvature to transient NC and also implies that transient and steady-state NC cannot be observed in a FE capacitor simultaneously. Finally, using the transient NC measurements, a procedure to experimentally determine the viscosity coefficient is presented to provide more insight into the relation between transient NC and the FE free-energy profile.

• Received 30 August 2017
• Revised 3 November 2017

DOI:https://doi.org/10.1103/PhysRevApplied.9.014010