Anomalous response in the vicinity of spontaneous symmetry breaking

TL;DR

This paper introduces a mechanism to achieve negative AC permittivity near ferroelectric phase transitions by exploiting responses at low frequency, supported by analytical and numerical studies of spin models.

Contribution

It presents a novel mechanism for negative permittivity near phase transitions, combining analytical and numerical analysis of spin systems with spontaneous symmetry breaking.

Findings

Negative AC permittivity can be induced near phase transition points.

The mechanism results in high gain and large phase delay.

Numerical simulations support the analytical predictions.

Abstract

We propose a mechanism to induce negative AC permittivity in the vicinity of a ferroelectric phase transition involved with spontaneous symmetry breaking. This mechanism makes use of responses at low frequency, yielding a high gain and a large phase delay, when the system jumps over the free-energy barrier with the aid of external fields. We illustrate the mechanism by analytically studying spin models with the Glauber-typed dynamics under periodic perturbations. Then, we show that the scenario is supported by numerical simulations of mean-field as well as two-dimensional spin systems.