LAUSR

In the last few decades, piezoresponse force microscopy (PFM) has been a valuable tool to analyze ferroelectric materials at nanoscale. Domain switching and phase-hysteresis loops acquired by PFM had been taken as a proof of ferroelectricity; however, these two characteristics have been observed in non-ferroelectric materials, generating uncertainty of the characterizations carried out by PFM. To resolve this problem, strategies have been developed but they are difficult to implement or still fail depending on the measurement conditions. In this work, we provide a simple method to effectively differentiate ferroelectric from non-ferroelectric signals in PFM analyses. It is based on the comparison of the phases of the PFM signals obtained at the first and the second harmonics of the contact resonant frequency of the Vac applied between the tip and the bottom electrode. To illustrate the effectiveness and simplicity of the method, analyses were conducted on a ferroelectric PZT film, a non-ferroelectric glass and SrTiO3 sample, and a KNN ceramic with ferroelectric and non-ferroelectric zones.