Internal magnetic field effect on magnetoelectricity in orthorhombic $RMn{O}_3$ crystals

Abstract

We have investigated the role of the 4$f$ moment on the magnetoelectric (ME) effect of orthorhombic $R$MnO${}_3$ ($R$=rare earth ions). In order to clarify the role of the 4$f$ moment, we prepared three samples: (Eu,Y)MnO${}_3$ without the 4$f$ moment, TbMnO${}_3$ with the anisotropic 4$f$ moment, and (Gd,Y)MnO${}_3$ with the isotropic 4$f$ moment. The ferroelectric behaviors of these samples are different from each other in a zero magnetic field. (Eu,Y)MnO${}_3$ and (Gd,Y)MnO${}_3$ show the ferroelectric polarization along the a axis in the ground state, while TbMnO${}_3$ shows it along the c axis. Such difference may arise from the influence of the anisotropic Tb${}^{3+}$ 4$f$ moment. The direction of the ferroelectric polarization of $R$MnO${}_3$ is determined by the internal magnetic field arising from the 4$f$ moment.

2 pages, 1 figure, the proceeding of International Conference of Magnetism, to be published in the Journal of Magnetism and Magnetic Materials