Giant tunability of ferroelectric polarization in GdMn₂O ₅

Giant tunability of ferroelectric polarization (ΔP=5000 μC/m2) in the multiferroic GdMn₂O₅ with external magnetic fields is discovered. The detailed magnetic model from x-ray magnetic scattering results indicates that the Gd-Mn symmetric exchange striction plays a major role in the tunable ferroelectricity of GdMn₂O₅, which is in distinction from other compounds of the same family. Thus, the highly isotropic nature of Gd spins plays a key role in the giant magnetoelectric coupling in GdMn₂O₅. This finding provides a new handle in achieving enhanced magnetoelectric functionality.