Univ Maryland Dept Phys Ctr Superconduct Res College Pk Md 20742
Max Planck Inst Festkorperforsch D-70569 Stuttgart Germany

Spin-fluctuation-mediated superconductivity is conventionally associated with d(x2-y2) pairing. We show that a generalized model of antiferromagnetic spin fluctuations in three dimensions may also yield a state with formal ''s-wave'' (A(1g)) symmetry but with line nodes at k(z) approximate to +/- pi/2c. We study this state within both BCS and Eliashberg theories using a realistic band structure and find that it is more stable than the d(x2-y2) (B-1g) state over a wide range of parameters. Thus, models of spin-fluctuation-mediated superconductivity must Consider both possibilities on an equal footing.
 

Physical Review B, 53 5137-5140, 1996.