Probing ferroelectric switching via spatially averaged hysteresis loops in rough thin films

Accurate characterization of polarization switching in ferroelectric thin films is critical for their effective integration into functional devices. Among the key parameters used to evaluate the polarization switching behavior, the bias switching voltages and the imprint can easily be obtained from ferroelectric polarization-driven hysteresis loops obtained by piezoresponse force microscopy (PFM). Although local "point & shoot" PFM measurements can provide reliable results on atomically flat films, their application to rough surfaces requires extensive data collection over numerous points, making the process tedious and time consuming. In order to obtain faster results and reduce artifacts, we propose here a rapid and effective method based on readily averaged hysteresis loop measurements. In particular, we demonstrate in the case of rough Bi2FeCrO6 ferroelectric films a spatially averaged off-field hysteresis loop acquisition method that mitigates morphology-induced inhomogeneities and electrostatic field effects. This methodology enables the accurate extraction of ferroelectric switching parameters regardless of the film roughness, offering a robust and efficient alternative for characterizing a wide range of ferroelectric thin films.