Negative exchange bias in single-phase Dy1-xNdxCrO3 induced by Nd doping

Observation of significant negative exchange bias ( HE) is reported in solid solutions of single-phase samples of Dy1-xNdxCrO3 for x = 0.33, 0.67, and 1 with corresponding Neel temperatures at T-N(Cr) = 175K, 200K, and 225 K, respectively, and the spin-reorientation transitions T-SR at 48 K, 58 K, and 38 K, respectively. In contrast, no HE was observed for the sample with x = 0 (i.e., DyCrO3) shows no HE below its T-N(Cr) = 145 K, and no reorientation of spins at lower temperatures was observed. More importantly, the (negative) HE for the x = 0.33, 0.67, and 1 samples is observed only in the temperature range between T-N and TSR with the corresponding observation of magnetic coercivity. These results show that the canted antiferromagnetic Gamma(7),(Cr) structure of the Cr3+ moments present between T-N(Cr) and TSR is essential for the observed HE. By comparing this result to the literature, common features of single-phase materials with HE were identified. The present bulk powder samples were prepared by the citrate method and structurally characterized by x-ray diffraction and Raman spectroscopy techniques. Neutron diffraction measurements for the x = 0.33, 0.67, and 1 samples at select temperatures were done to verify the presence of the Gamma(7,Cr) structure between T-N(Cr) and TSR and the Gamma(1,Cr) structure (with no canting of Cr3+ moments) below TSR