The interplay of magnetic order and superconductivity in GdxY1−xNi2B2C

Resistivity, ac susceptibility and magnetization measurements are reported for polycrystalline samples of the Gd x Y 1− x Ni 2 B 2 C series as a function of temperature and magnetic field. The magnetic Gd impurities cause an almost linear decrease of the superconducting transition temperature T c with increasing Gd content in the range of x T c have been observed. The effect of the 4f local moments manifests in a complete suppression of superconductivity for x ⩾0.3 and in antiferromagnetic ordering for x >0.3. In zero applied magnetic field, a distinct concentration region around x ∼0.3 has been revealed separating superconductivity and antiferromagneting ordering. A metamagnetic transition has been observed in the compound with x =0.5 at a magnetic field of 0.8 T.