Magnetism and superconductivity in Y1-xTbxNi2B2C single crysta-ls.

Abstract

The magnetic and superconducting properties in a series of pseudo-quaternary compounds Y1-xTbxNi2B2C were investigated by the temperature-dependent magnetization M(T) for applied field parallel and perpendicular to the c axis and by in-plane resistivity, rho (T). There was a large anisotropy in M(T), which is attributed to the crystalline electric field effects. As the Tb concentration x is increased, the superconducting transition temperature T-c decreases and disappears rapidly in the vicinity of x=0.4 while the Neel temperature T-N appears abruptly near x=0.4 and increases with Tb content. In addition, the increase of M(T) at low temperatures below T-N was observed for x greater than or equal to0.4, of which the onset temperature T-WF is regarded as development of weak-ferromagnetic component. Tw, was also in proportion to the Tb content x accompanied by T-N. The linear decrease of T-c for dilute Tb concentration seems to follow an Abrikosov-Gor'kov expectation, while the sudden destruction of T-c near x=0.4 seems to have close correlation with the emergence of magnetic states, i.e., antiferromagnetic and weak-ferromagnetic states. Possible scenarios for the correlation are discussed.