Magnetic-Field and External-Pressure Effect on Ferroelectricity in Manganites: Comparison between GdMnO$_{3}$ and TbMnO$_{3}$

TL;DR

This study compares the effects of magnetic fields and external pressure on ferroelectricity in GdMnO₃ and TbMnO₃, revealing different transition types and pressure responses in these manganites.

Contribution

It provides a comparative analysis of ferroelectric transitions in GdMnO₃ and TbMnO₃ under external stimuli, highlighting their distinct transition mechanisms.

Findings

GdMnO₃ exhibits first-order displacive-type ferroelectric transition.

TbMnO₃ shows second-order order-disorder-type transition.

External pressure suppresses ferroelectricity in GdMnO₃ and shifts transition temperature in TbMnO₃.

Abstract

We have investigated dielectric properties in Mott insulators GdMnO$_{3}$ and TbMnO$_{3}$ under magnetic fields and external quasihydrostatic pressures. In the case of GdMnO$_{3}$, thermal hysteresis for dielectric constant $\epsilon$ and discontinuous lattice distortion were observed at ferroelectric transition temperature ($T_{C}$), and ferroelectric spontaneous polarization was suppressed by application of external pressure. These results indicate that the ferroelectric transition in GdMnO$_{3}$ is a first-order displacive-type one. On the other hand, the thermal hysteresis and discontinuous lattice striction were not observed at $T_{C}$ in TbMnO$_{3}$. The peak of $\epsilon$ corresponding to ferroelectric transition was shifted toward higher temperatures by application of external pressure in TbMnO$_{3}$. The ferroelectric transition of TbMnO$_{3}$ was thought to be a second-order order-disorder-type one.