Superconductivity has been observed in ${\mathrm{DyNi}}_2$${\mathrm{B}}_2$C single crystals at 6.4 K. ${\mathrm{DyNi}}_2$${\mathrm{B}}_2$C also orders antiferromagnetically at ∼10.5 K and is a unique member of R${\mathrm{Ni}}_2$${\mathrm{B}}_2$C compounds (R=Y or rare earth) in that the onset of superconductivity takes place in a magnetically ordered state. The crystals exhibit anomalous field-cooled magnetization in low applied fields of 1–5 Oe. Specific-heat measurements on the crystals give further evidence for the bulk nature of the magnetic order. The upper critical field ${\mathit{H}}_{\mathit{c}2}$ measured parallel and perpendicular to the c axis of the crystals, shows little or no anisotropy. ${\mathit{H}}_{\mathit{c}2}$(0) for ${\mathrm{DyNi}}_2$${\mathrm{B}}_2$C is deduced to be 0.7 T.

• Received 25 April 1995

DOI:https://doi.org/10.1103/PhysRevB.52.9186