Landau-Ginzburg-Devonshire theory for electromechanical hysteresis loop formation in piezoresponse force microscopy of thin films

TL;DR

This paper develops a Landau-Ginzburg-Devonshire theoretical model to analyze the formation of electromechanical hysteresis loops in ferroelectric thin films during piezoresponse force microscopy, considering tip size, film thickness, and frequency effects.

Contribution

It introduces a LGD-based approach that accounts for polarization-dependent piezoelectric response and kinetics, improving understanding of PFM hysteresis loop shapes.

Findings

The model explains non-classical PFM loop shapes.

It shows the influence of tip size and frequency on hysteresis.

The approach integrates thermodynamics and kinetics of polarization reversal.

Abstract

Electromechanical hysteresis loop formation in piezoresponse force microscopy of thin ferroelectric films is studied with special emphasis on the effects of tip size and film thickness, as well as dependence on the tip voltage frequency. Here, we use a combination of Landau-Ginzburg-Devonshire (LGD) theory for the description of the local polarization reversal with decoupling approximation for the calculation of the local piezoresponse loops shape, coercive voltages and amplitude. LGD approach enables addressing both thermodynamics and kinetics of hysteresis loop formation. In contrast to the "rigid" ferroelectric approximation, this approach allows for the piezoelectric tensor components dependence on the ferroelectric polarization and dielectric permittivity. This model rationalizes the non-classical shape of the dynamic piezoelectric force microscopy (PFM) loops.