  We theoretically explore mechanisms that can potentially give rise to the
steady-state and transient negative capacitance in a uniaxial ferroelectric
film stabilized by a dielectric layer. The analytical expressions for the
steady-state capacitance of a single-domain and poly-domain states are derived
within Landau-Ginzburg-Devonshire approach and used to study the state
stability vs. the domain splitting as a function of dielectric layer thickness.
Analytical expressions for the critical thickness of the dielectric layer,
polarization amplitude, equilibrium domain period and susceptibility are
obtained and corroborated by finite element modelling. We further explore the
possible effects of nonlinear screening by two types of screening charges at
the ferroelectric-dielectric interface and show that if at least one of the
screening charges is very slow, the total polarization dynamics can exhibit
complex time- and voltage dependent behaviors that can be interpreted as an
observable negative capacitance. In this setting, the transient negative
capacitance effect is accompanied by almost zero dielectric susceptibility in a
wide voltage range and low frequencies. These results may help to elucidate the
observation of the transient negative capacitance in thin ferroelectric films,
and identify materials systems that can give rise to the behavior.
