Pomeranchuk instability on a two-dimensional frustrated lattice

Abstract

We investigate the Pomeranchuk instability (PI) in the two-dimensional extended Hubbard model with frustration using the variational cluster approach. The system shows a tendency toward the PI which breaks the tetragonal symmetry of the Fermi surface. However, a pure superconducting state with isotropic underlying lattice is more favored for weak nearest-neighbor repulsion $V$. As $V$ is increased beyond the critical value, superconductivity is suppressed and the system undergoes a first-order transition to the PI. We find that the local density of states (LDOS) shows interesting behavior in the presence of Fermi-surface symmetry breaking. The low-energy feature of LDOS is sharp and the spectral weight remarkably transfers from low-energy peaks to the local minimum near the Fermi level. Meanwhile, the high-energy feature remains almost unchanged. Based on these findings, we can establish a potential relationship between the PI and metamagnetic transition in the bilayer ruthenate ${\text{Sr}}_{3}{\text{Ru}}_{2}{\text{O}}_{7}$.