Order Of Dy Moments Research Articles

The origin of multiple magnetic and dielectric anomalies of Mn-doped DyMnO3 in low temperature region

The solid solution (Dy1−xMnx)MnO3−δ (0.037 ≤ x ≤ 0.142) has been synthesized by the conventional solid-state method. Powder X-ray diffraction and selected area electron diffraction reveal that all the samples crystallize in the space group Pnma. The magnetic and dielectric studies on Mn-doped DyMnO3 reveal existence of three anomaly behaviors in low temperature region. A transition from an incommensurate antiferromagnetic ordering of Mn3+ spins at T1 ∼ 37 K, a lock-in transition at TC1 ∼ 18 K. The second antiferromagnetic transition at T2 ∼ 7 K, originating from the ordering of Dy moments with a slight Mn doping range of 0.037 ≤ x < 0.087, and it disappears with 0.087 ≤ x ≤ 0.142 due to damage of the Dy spin ordering. Interestingly, the Mn doping in DyMnO3 suppresses the ferroelectric ordering, resulting in reduction in ferroelectric ordering temperatures, whereas an increase in antiferromagnetic transition temperatures has been observed.

Phase Equilibria in the System Al2O3-CaO-CoO and Gibbs Energy of Formation of Ca3CoAl4O10

The floating-zone method with different growth ambiences has been used to selectively obtain hexagonal or orthorhombic DyMnO3 single crystals. The crystals were characterized by x-ray powder diffraction of ground specimens and a structure refinement as well as electron diffraction. We report magnetic susceptibility, magnetization and specific heat studies of this multiferroic compound in both the hexagonal and the orthorhombic structure. The hexagonal DyMnO3 shows magnetic ordering of Mn3+ (S = 2) spins on a triangular Mn lattice at T-N(Mn) = 57 K characterized by a cusp in the specific heat. This transition is not apparent in the magnetic susceptibility due to the frustration on the Mn triangular lattice and the dominating paramagnetic susceptibility of the Dy3+ (S = 9/2) spins. At T-N(Dy) = 3 K, a partial antiferromagnetic order of Dy moments has been observed. In comparison, the magnetic data for orthorhombic DyMnO3 display three transitions. The data broadly agree with results from earlier neutron diffraction experiments, which allows for the following assignment: a transition from an incommensurate antiferromagnetic ordering of Mn3+ spins at T-N(Mn) = 39 K, a lock-in transition at Tlock-in = 16 K and a second antiferromagnetic transition at T-N(Dy) = 5 K due to the ordering of Dy moments. Both the hexagonal and the orthorhombic crystals show magnetic anisotropy and complex magnetic properties due to 4f-4f and 4f-3d couplings.