The crucial role of Mn spiral spin order in stabilizing the Dy–Mn exchange striction in multiferroic DyMnO₃

Abstract

DyMnO hosts the less addressed duality of multiferroicity, owing to the Dy-Mn exchange striction and inverse Dzyaloshinskii-Moriya interaction between Mn spin pairs. Although the duality in DyMnO has been discussed earlier, there remains a question whether the Mn magnetic sublattice is necessarily multiferroic for generating the Dy-Mn exchange striction. In this work, we investigate the multiferroicity of Dy(MnFe)O (0 ≤ x ≤ 0.1) through detailed magnetic and ferroelectric characterization. It is found that Fe-doping continuously suppresses the independent Dy spin order but instead promotes the Dy-Mn(Fe) coupling. This coupling benefits the Dy-Mn(Fe) exchange striction which remarkably enhances the ferroelectric polarization at a low doping level (x ≤ 0.015), beyond which the Mn spiral spin order breaks down leading to collapse of the macroscopic polarization at x ≥ 0.05. This work discloses the crucial role of Mn spiral spin order in stabilizing the Dy-Mn exchange striction and thus highlights the duality of multiferroicity in DyMnO.

The effect of rare-earth Gd-substitution on the structural, magnetic and specific heat properties in orthorhombic DyMnO3 ceramics

“…The substitution of a small concentration of Al (≤0.01) at the Mn-site of DyMnO 3 is effective in increasing the ferroelectric polarization in DyMnO 3 [16]. The suppression of the Dy spin ordering and the enhancement of the Dy-Mn(Fe)-exchange interaction, leading to the increase in ferroelectric behavior, is argued to be due to Fe-doping on the Mn-site of DyMnO 3 [17]. A possible way of examining the striction may be via phonon dynamics, which provides microscopic insight into the lattice structure such as structure-property relations, mode softening and local ordering in the crystal [18].…”