MAGNETIC-STRUCTURE AND SUPERCONDUCTIVITY IN (HOXY1-X)NI2B2C

The superconducting transition and the magnetic structure of polycryst alline (HoxY1-x)Ni2B2C have been investigated for x greater than or eq ual to 0.75 by resistivity measurements and neutron diffraction, respe ctively. For HoNi2B2C, the well known antiferromagnetic structure with c- and a-axis components existing between 4.5 and 6 K has been confir med. Whereas for all investigated samples the component having the a-a xis modulated structure exists in a narrow temperature range only, the intensity connected to the spiral magnetic state along the c-axis inc reases for x=0.85 and x=0.75 monotonically as the temperature decrease s to the lowest measuring temperature of 1.6 K. Our results strongly s uggest that the incommensurate modulated structure along the a-axis is responsible for pair breaking in the investigated (HoxY1-x)Ni2B2C sam ples. On the other hand, the magnetic spiral structure with c-axis wav e vector was found to coexist with superconductivity. A linear suppres sion of the superconducting transition temperature with increasing Ho content was observed which is in agreement with the Abrikosov-Gor'kov theory. We found a linear scaling with the effective de Gennes factors (x DG) (He) for both the superconducting transition and the magnetic ordering temperatures. (C) 1997 American Institute of Physics.