Multiferroicity in orthorhombic RMnO3 (R = Dy, Tb, and Gd) under high pressure

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 pressure, all of these manganites were found to exhibit ferroelectricity in which spontaneous polarization (approximate to 10 degrees mu C/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 Delta P(B) = 1.3 mu C/ cm(2). A possible origin of the observed R-dependent pressure effect is discussed.