Pairing due to the exchange of magnetic fluctuations in cuprate superconductors

The possibility for a superconducting instability due to the exchange of magnetic fluctuations is studied by means of low-density expansion. It is shown that if the magnetic fluctuations are centered at (π,π), they uniquely favor dx2-y2 superconductivity close to the magnetic instability no matter at which doping concentration this instability occurs. However, if the magnetic fluctuations are centered around the incommensurate (π(1-δ),π) point in the Brillouin zone, they tend to suppress any type of superconductivity.