Magnetocapacitance effect and related microstrucuture in Ti-dopedYMnO3

Abstract

We have investigated microstructures giving rise to magnetocapacitance effect in Ti-doped $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$ $(\mathrm{Y}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}{\mathrm{O}}_{3})$ by both electron diffraction and real-space imaging techniques. Diffuse scattering elongating along the [110] direction due to the instability of the Mn trimerization were found in the $x=0.175$ compound, which exhibits the enhanced magnetocapacitance effect. With increasing Ti concentration, the centrosymmetric (paraelectric) $R\overline{3}c$ phase grows up at the expense of the ferroelectric $P{6}_{3}cm$ phase around $x=0.20$ and the $R\overline{3}c$ phase is dominant above $x=0.30$. Our present results indicate that the Mn trimers with the short-range correlation inside the ferroelectric nanodomains with the $10--20\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ size should be responsible for the enhancement of the magnetocapacitance and, on the other hand, the appearance of the $R\overline{3}c$ phase suppressed the magnetocapacitance effect.