Multiferroic Properties in Orthorhombic RMnO3 (R=Dy, Tb, and Gd) under High Pressures

The hydrostatic pressure effect on multiferroic properties of rare-earth manganites RMnO3 (R=Dy, Tb, and Gd) with the Pbnm orthorhombic structure was investigated by using a diamond anvil cell. Under high pressures, all of these manganites were found to exhibit ferroelectricity in which spontaneous polarization (≈100 µC cm－2) develops along the a axis. The application of a magnetic field B along the a axis to the high-pressure ferroelectric phase causes a drastic change in the electric polarization P. Especially in GdMnO3, the B-induced change in P reached ΔP(B)=1.3 µC cm－2. A possible origin of the observed R-dependent pressure effect is discussed.