Specific-heat study on successive magnetic transitions in α-Dy2S3 single crystals under magnetic fields

Specific-heat measurements in magnetic fields have been performed on α-Dy2S3 single crystals and have shown successive magnetic transitions at \(T_{N_1 } = 11.4 K\) and \(T_{N_2 } = 6.4 K\). The specific heat in no magnetic field exhibits sharp peaks at both \(T_{N_1 }\) and \(T_{N_2 }\). The change in the magnetic entropy across each transition is estimated as Rln2/2 per mol-Dy, which suggests magnetic moments on only one Dy site between two crystallographically inequivalent Dy sites order at each transition temperature. When the magnetic field is applied along the b-axis of the orthorhombic system, the two peaks of the specific heat shift toward lower temperatures. On the other hand, a magnetic field perpendicular to the b-axis shifts the peaks toward higher temperatures. The \(T_{N_1 }\) shifts to 9.6 K (H ‖ b) and 12.5 K (H ⊥ b) under a magnetic field of 2 T. The \(T_{N_2 }\) peak broadens gradually with increasing magnetic field for each direction; consequently, the peak is obscure under a field of 2 T.