Coexistence of antiferromagnetic order and superconductivity with TN higher than Tc in DyNi 2B 2C

Abstract

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 DyNi 2B 2C 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 − αB 2 − βC 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 Dy 3+ 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.