  The local hysteresis loop obtained by switching spectroscopy piezoresponse
force microscopy (SS-PFM) is usually regarded as a typical signature of
ferroelectric switching. However, such hysteresis loops were also observed in a
broad variety of non-ferroelectric materials in the past several years, which
casts doubts on the viewpoint that the local hysteresis loops in SS-PFM
originate from ferroelectricity. Therefore, it is crucial to explore the
mechanism of local hysteresis loops obtained in SS-PFM testing. Here we
proposed that non-ferroelectric materials can also exhibit amplitude butterfly
loops and phase hysteresis loops in SS-PFM testing due to the Maxwell force as
long as the material can show macroscopic D-E hysteresis loops under cyclic
electric field loading, no matter what the inherent physical mechanism is. To
verify our viewpoint, both the macroscopic D-E and microscopic SS-PFM testing
are conducted on a soda-lime glass and a non-ferroelectric dielectric material
Ba0.4Sr0.6TiO3. Results show that both materials can exhibit D-E hysteresis
loops and SS-PFM phase hysteresis loops, which can well support our viewpoint.
