Theory of spontaneous Fermi surface symmetry breaking for [formula omitted

Abstract

We show that many salient features observed around the metamagnetic transition in Sr 3 Ru 2 O 7 are described within a simple model, which considers only an instability of the Fermi surface symmetry breaking (Pomeranchuk instability), without invoking a putative metamagnetic quantum critical end point as usually assumed for this compound. In our model, the Pomeranchuk instability and unconventional, non-Fermi liquid type properties arise due to the tuning of the van Hove singularity of either a majority or a minority spin band to the vicinity of the Fermi energy by a magnetic field. The obtained phase diagram, the metamagnetic transition, and the temperature dependence of the magnetic susceptibility and specific heat show striking similarities to the experimental data.