Magnetoelectric coupling and lattice dynamics of Gd-doped BiFeO3 multiferroics

The Bi1−xGdxFeO3 (x = 0 − 0.2) ceramics were prepared by a solid-state reaction technique. Studies of magnetic and magnetoelectric properties were carried out. Due to the R3c → Pnma structural change, the spiral modulated spin structure collapses continuously with increasing Gd content and strongly enhances magnetization and magnetoelectric coefficient at x > 0.1. Studies of lattice dynamics of pure BiFeO3 were conducted ab-initio by means of density functional theory in order to shed light on ferroelectric instability.