Coexistence of antiferromagnetic order and superconductivity with T_N higher than T_c in DyNi₂B₂C

A superconducting transition temperature T_c of 3.8 K with an onset as high as 5.2-5.5 K was reported for quaternary borocarbide DyNi₂B₂C with a high antiferromagnetic Néel temperature T_N around 10.1-10.8 K. No reentrant behavior was observed down to 0.3 K demonstrating a perfect coexistence between superconductivity and antiferromagnetic order. A superconducting upper critical field H_c2(0) of 3.0 kG, lower critical field H_c1(0) of 200 G and Ginzburg-Landau parameter κ of 3.7 were derived. A broad T_c transition points to a possible small T_c varying homogeneity range of DyNi_{2 - α}B_{2 - β}C_{1 - δ} in the phase diagram. The magnetic entropy S_m of 10.3 J/mol K or 90% Rln 4 indicates antiferromagnetic ordering of Dy³⁺ with a quadruplet ground state in the tetragonal crystal field. Two field-induced weak-ferromagnetic-like transitions with a field of around 1 T were observed at 2 K.