Atomic-Scale Domain Mediation in Nd-Doped BiFeO₃ Film

A large number of applications involving ferroelectric materials are substantially influenced by domain walls (DWs). Especially, charged DWs (CDWs) show great potentials in controlling the switching mechanism and the electric and piezoelectric properties of ferroelectric materials. In the present 5% Nd-doped BiFeO3 film, besides the uniformly downward polarization in the film matrix, special domain configurations including 71° CDW and the adjacent inserting nanodomain as well as the resulting DW junction near the film surface have been quantitatively resolved by aberration-corrected scanning transmission electron microscopy. Direct polarization mapping of DWs combined with the unit-cell-wise strain map at an atomic scale demonstrate the accumulation of Nd at the CDWs. The favorable formation of the observed local domain configurations depends on the minimization of the total DW energy and the screening of bound charges accumulated at the local surface of the film.