Landau-Fermi liquids in disguise

TL;DR

This paper demonstrates that coherent quasiparticles can exist near Luttinger surfaces in interacting electron systems, challenging the belief that quasiparticles only exist near Fermi surfaces, and shows they exhibit conventional thermodynamic and dynamic properties.

Contribution

It reveals the existence of well-defined quasiparticles approaching Luttinger surfaces, with properties similar to those near Fermi surfaces, in strongly correlated electron systems.

Findings

Quasiparticles exist near Luttinger surfaces in compressible systems.

These quasiparticles exhibit quantum oscillations and linear specific heat.

Contradicts the common belief that quasiparticles only exist near Fermi surfaces.

Abstract

In periodic systems of interacting electrons, Fermi and Luttinger surfaces refer to the locations within the Brillouin zone of poles and zeros, respectively, of the single-particle Green's function at zero energy and temperature. Such difference in analytic properties underlies the emergence of well-defined quasiparticles close to a Fermi surface, in contrast to their supposed non-existence close to a Luttinger surface, where the single-particle density-of-states vanishes at zero energy. We here show that, contrary to such common belief, coherent `quasiparticles' do exist also approaching a Luttinger surface in compressible interacting electron systems. Thermodynamic and dynamic properties of such 'quasiparticles' are just those of conventional ones. For instance, they yield well defined quantum oscillations in Luttinger's surface and linear in temperature specific heat, which is striking given the vanishing density of states of physical electrons, but actually not uncommon in strongly correlated materials.