Pomeranchuk instability of spin-antisymmetric channel in Sr _3Ru _2O _7

摘要

We study a possible Pomeranchuk instability in the "nematic phase" in Sr _3Ru _2O _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 _3Ru _2O _7.