Pulse-controlled generation and characterization of partially-switched multiple-value polarization states in PZT ceramics

This paper explores in depth the partially switched states of ferroelectrics, through macroscopic polarization measurements in conjunction with piezoresponse force microscopy, x-ray diffraction and dielectric characterization, with the ultimate purpose to explore their usefulness for unconventional multiple-value nonvolatile memory applications. We prove that it is possible to reproducibly generate analog levels of polarization in a Pb(Zr,Ti)O3 ferroelectric ceramic capacitor and control them with electric pulses that stabilize unique domain patterns, compatible with those of adjacent states. Some of these states contain, in the same locations of the sample surface, areas with orientation of polarization vector opposite to that of the electric field that decides the analog polarization level, while others contain clamped domain structures with reduced piezoelectric activity. We argue that disclosing the complex relationships between the domain structures of the analog polarization states, as well as their dependence on write voltage parameters, might help to expand the multiple-value storage capability of ferroelectrics beyond what would be achievable on macroscopic scale.