On the Magnetically Driven Ferroelectric Phase in GdMnO₃

Abstract

At room temperature, GdMnO ₃ 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 ( = δ (T)*; T _c1 = 42 K) and a A-type antiferromagnetic phase (T _c2 = 27 K). At low temperatures (T ≤ 12 K), a magnetic field applied along the a-axis destabilizes the antiferromagnetic phase and induces a first order transition to a magnetic commensurate modulated phase ( = 1/4 *) that is also ferroelectric (//). This work analyses this field induced phase transition from the point of view of the symmetry and Landau theory.

Keywords:

• Magnetoelectric materials
• rare-earth manganites
• modulated phases