Doping Effect on Interlocked Ferroelectric and Structural Antiphase Domains in YMnO3

Changes in ferroelectric and structural antiphase domain structure by the partial substitution of nonmagnetic Ti4+ ions at the Mn site were investigated carefully by electron diffraction, dark-field imaging, and high-resolution lattice imaging experiments. The ferroelectric and structural antiphase domains are revealed to be mutually interlocked in YMnO3 and, on the other hand, when x was increased up to x similar to 0.30 in YMn1-xTixO3, the ferroelectric domains disappeared and the size of the structural antiphase domains decreased to approximately 10nm at x similar to 0.30. High-resolution lattice images clearly demonstrate the coexisting state of nanodomains characterized by the modulated structure due to the structural trimerization and the nonmodulated structures. Our experimental results suggest that a partial substitution of Ti4+ ions suppressed the ferroelectric displacement along the [001] direction and the correlation length of the Mn3+ trimerization decreased. (c) 2012 The Japan Society of Applied Physics