THE INTERPLAY BETWEEN MAGNETISM AND SUPERCONDUCTIVITY IN RNI(2)B(2)C (R=LU, TM, ER, HO, DY, TB, GD)

The superconducting and magnetic phase diagram (characteristic tempera tures versus effective ionic radii) of the RNi(2)B(2)C (R=Lu, Tm, Er, Ho, Dy, Tb, Gd) compounds are considered. Although the gradual degrada tion of superconductivity can be scaled to the de Gennes factor, (g-1) (2)J(J+1), the unique reentrant behavior of the HoNi2B2C compound and the abrupt quenching of superconductivity for R lighter than Ho are mo st probably unaccountable within this scheme. Rather, it is argued tha t their low-T magnetic and transport properties as well as the main fe atures of the interplay between magnetism and superconductivity can be accounted for if the low-T magnetism of HoNi2B2C, as reported by Grig ereit et al., is generalized to the other isomorphous R members. Thus the onset of the 4f moments antiferromagnetic state at T-1 is accompan ied by an oscillatory component, which transforms to a commensurate an tiferromagnetic state at T-2. For HoNi2B2C, the pressure and magnetic- field influence on T-c, T-1 and T-2 will be discussed.