Domain Patterns and Electric Properties at Domain Walls in a Surface Normal to the Direction of Ferroelectric Polarization in h-ErMnO₃

The configuration of ferroelectric domains in a plane normal to the direction of ferroelectric polarization in hexagonal ErMnO₃ (h-ErMnO₃) was investigated using piezoresponse force microscopy and a three-dimensional Monte Carlo simulation of the clock model with a third dimensional coupling. Two kinds of patterns, long-range-ordered stripe domains and swirling vortex domains were observed alternatively depending on the crystal's annealing temperature. From the Monte Carlo simulation, these vortex domain and stripe domain patterns could be understood as the topologies of an intermediate state and the ground state of the h-ErMnO₃ crystal, respectively. The detailed electric properties of the polarization configuration were obtained by using conductive atomic force microscopy and revealed a tail-to-tail polarization configuration at the domain boundary that demonstrated a more conductive character than the head-to-head polarization configuration.