Interband Coulomb Interaction and Horizontal Line Nodes in Triplet Superconductor Sr2RuO4

A possible mechanism for appearance of the horizontal line nodes in triplet superconductor, Sr 2 RuO 4 , is proposed. We consider the interlayer Coulomb interaction, as well as the on-site Coulomb repulsion, between electrons in different bands. In the second order perturbation of the interband interaction, the effective interaction becomes dependent on \(\cos \frac{q_z}{2}\), resulting in horizontal line nodes.