Switching of Ferroelectrics Without Domains

It has been known since the 1930s that ferroelectrics could theoretically reverse polarization without domain wall motion. Occasionally experimental reports claim such effects. This essay reviews the history and new evidence from Lei Zheng for this in polyvinylidene (PVDF) copolymers: two distinct critical fields and a limited temperature range (accompanying figure) for paraelectric-ferroelectric transitions induced by an applied field.