Pomeranchuk Instability of Spin-Antisymmetric Channel in Sr3Ru2O7

We study a possible Pomeranchuk instability in the "nematic phase" in Sr 3 Ru 2 O 7 by calculating the Landau interaction function on the basis of an extended $d$--$p$ model with the on-site Coulomb interaction $U_{pp}$ between $2p$ electrons at the O site. We find that the spin-antisymmetric $p$-wave type instability becomes dominant within the second-order perturbation theory with respect to the on-site Coulomb interactions $U_{pp}$ and $U_{dd}$ which is the conventional interaction between $4d$ electrons at the Ru site. Furthermore, within the mean field theory, we obtain a temperature vs magnetic field phase diagram, which is consistent with that observed in Sr 3 Ru 2 O 7 .