Spin-liquid insulators can be Landau's Fermi liquids

TL;DR

This paper demonstrates that certain spin-liquid insulators exhibiting metallic-like thermal and magnetic properties can be understood within Landau's Fermi liquid framework by considering the concept of a Luttinger surface of zeros in the Green's function.

Contribution

It shows that spin-liquid insulators with spinon Fermi surfaces can be described as Landau Fermi liquids through the concept of a Luttinger surface, bridging a gap between insulator behavior and Fermi liquid theory.

Findings

Observation of quantum oscillations in Mott insulators.

Proposal that spinon Fermi surfaces are compatible with Landau's Fermi liquid theory.

Identification of a Luttinger surface of zeros in the Green's function.

Abstract

The long search for insulating materials that possess low-energy quasiparticles carrying electron's quantum numbers except charge - inspired by the neutral spin-1/2 excitations, the so-called spinons, exhibited by Anderson's resonating-valence-bond state - seems to have reached a turning point after the discovery of several Mott insulators displaying same thermal and magnetic properties as metals, including quantum oscillations in a magnetic field. Here, we show that such anomalous behaviour is not inconsistent with Landau's Fermi liquid theory of quasiparticles at a Luttinger surface. That is the manifold of zeros within the Brillouin zone of the single-particle Green's function at zero frequency, and which thus defines the spinon Fermi surface conjectured by Anderson.