The superconductivity and the magnetism of ${\mathrm{Dy}}_{1-x}{\mathrm{Tb}}_x{\mathrm{Ni}}_2{\mathrm{B}}_2\mathrm{C}$ $(0.0⩽x⩽1.0)$ single crystals were studied. As ${\mathrm{Tb}}^{+3}$ was substituted for ${\mathrm{Dy}}^{+3}$, the superconducting transition temperature $T_c$ decreased linearly at a rate of $d{T}_c∕dx=-12\mathrm{K}$, and for $x⩾0.4$, no superconductivity was observed above $2\mathrm{K}$. In contrast, the antiferromagnetic ordering temperature $T_N$ was almost constant for $x⩽0.6$. These behaviors are in sharp contrast to the case of ${\mathrm{Dy}}_{1-x}{\mathrm{Ho}}_x{\mathrm{Ni}}_2{\mathrm{B}}_2\mathrm{C}$, where the $T_c$ is constant for $x<0.7$ but the $T_N$ decreases linearly with $x$. The difference between ${\mathrm{Dy}}_{1-x}{\mathrm{Tb}}_x{\mathrm{Ni}}_2{\mathrm{B}}_2\mathrm{C}$ and ${\mathrm{Dy}}_{1-x}{\mathrm{Ho}}_x{\mathrm{Ni}}_2{\mathrm{B}}_2\mathrm{C}$ can be understood if the magnetic structures of both compounds are properly considered.

• Received 13 May 2005

DOI:https://doi.org/10.1103/PhysRevB.72.054516