Magnetic-field-induced switching between ferroelectric phases in orthorhombic-distortion-controlled $R$MnO${}_3$

We have investigated the dielectric and magnetic properties of Eu${}_{0.595}$Y${}_{0.405}$MnO${}_3$ $without$ the presence of the 4$f$ magnetic moments of the rare earth ions, and have found two ferroelectric phases with polarization along the $a$ and $c$ axes in a zero magnetic field. A magnetic field induced switching from one to the other ferroelectric phase took plase in which the direction of ferroelectric polarization changed from the a axis to the c axis by the application of magnetic fields parallel to the a axis. In contrast to the case of TbMnO${}_3$, in which the 4$f$ moments of Tb${}^{3+}$ ions play an important role in such a ferroelectric phase switching, the magnetic-field-induced switching between ferroelectric phases in Eu${}_{0.595}$Y${}_{0.405}$MnO${}_3$ does not originate from the magnetic transition of the rare-earth 4$f$ moments, but from that of the Mn 3$d$ spins.