On the magnetically driven ferroelectric phase in GdMnO3

TL;DR

This paper investigates the magnetic field-induced ferroelectric phase in GdMnO3, analyzing the symmetry and Landau theory of the transition from antiferromagnetic to a ferroelectric phase at low temperatures.

Contribution

It provides a detailed symmetry and Landau theory analysis of the field-induced ferroelectric phase transition in GdMnO3.

Findings

Magnetic field along the a-axis induces a ferroelectric phase at low temperatures.

The transition involves a change from antiferromagnetic to a commensurate modulated phase.

The study offers a theoretical framework for understanding magnetically driven ferroelectricity.

Abstract

At room temperature, GdMnO3 is a paraelectric and paramagnetic with a distorted perovskite structure of orthorhombic symmetry (space group Pnma). On cooling, it undergoes a phase transition sequence to a magnetic incommensurate phase (k=delta a*; Tc1=42K) and a A-type antiferromagnetic phase (Tc2=27K). At low temperatures (T<12K), a magnetic field applied along the a-axis destabilizes the antiferromagnetic phase and induces a first order transition to a magnetic commensurate modulated phase (delta=1/4) that is also ferroelectric (P//c). This work analyses this field induced phase transition from the point of view of the symmetry and Landau theory.