MAGNETISM AND SUPERCONDUCTIVITY IN (RE)NI2B2C - THE CASE OF TMNI2B2C

The recently reported coexistence of an oscillatory magnetic order wit h wave vector Q = 0.241(-1) and superconductivity in TmNi2B2C is analy zed theoretically. It is shown that the oscillatory magnetic order and superconductivity interact predominantly via the exchange interaction between localized moments (LMs) and conduction electrons, while the e lectromagnetic interaction between them is negligible. In the coexiste nce phase of the clean TmNi2B2C the quasiparticle spectrum should have a line of zeros at the Fermi surface, giving rise to the power-law be havior of thermodynamic and transport properties. Two scenarios of the origin of the oscillatory magnetic order in TmNi2B2C are analyzed: (a ) due to superconductivity and (b) independently of superconductivity. Experiments in a magnetic field are proposed in order to choose betwe en them, (C) 1997 Elsevier Science B.V.