Ferroelectric ordering and magnetoelectric effect of pristine and Ho-doped orthorhombic DyMnO 3 by dielectric studies
Résumé
In this paper, the magnetoelectric coupling and ferroelectric ordering of the orthorhombic Dy1-xHoxMnO3 (x = 0 and 0.1) are studied from the magnetodielectric response of the polycrystalline samples. The dielectric study on the DyMnO3 reveals ferroelectric transition at 18 K along with an addition transition at 12 K. We suggest that the transition at 12 K could have originated from the polarization flop rather than being the rare earth magnetic ordering. The magnetodielectric study reveals a magnetoelectric coupling strength of 10%, which is stronger by two orders of magnitude in comparison to the hexagonal manganites. Surprisingly, the Ho3+ substitution in DyMnO3 suppresses the magnetoelectric coupling strength via the suppression of the spiral magnetic ordering. In addition, it also reduces the antiferromagnetic ordering and ferroelectric ordering temperatures. Overall, the studies show that the rare earth plays an important role in the magnetoelectric coupling strength through the modulation of spiral magnetic structure.