p -wave andd-wave superconductivity in quasi-two-dimensional metals

We compare predictions of the mean-field theory of superconductivity for nearly antiferromagnetic and nearly ferromagnetic metals in two dimensions. The calculations are based on a parametrization of the effective interaction arising from the exchange of magnetic fluctuations. The Eliashberg equations for the transition temperature are solved including the full momentum dependence of the electron self-energy. The results show that for comparable parameters d-wave singlet pairing in nearly antiferromagnetic metals is generally much stronger than p-wave triplet pairing in nearly ferromagnetic metals in quasi-two dimensions. The relevance to the layered materials, and in particular Sr₂RuO₄ that exhibits p-wave triplet pairing, is discussed.