Crossover from Fermi Arc to Full Fermi Surface

TL;DR

This paper models the evolution of the Fermi surface in doped Mott insulators, showing a transition from Fermi arcs to a full Fermi surface at a critical doping, with implications for understanding pseudogap and strange metal phases.

Contribution

It introduces a mean-field theory explaining the crossover from Fermi arcs to a full Fermi surface in doped Mott insulators, emphasizing quasiparticle fractionalization and spectral weight reduction.

Findings

Fermi arcs result from spectral weight reduction due to fractionalization

Full Fermi surface reappears beyond critical doping $oldsymbol{ ext{delta*}}$

Enhanced density of states at Fermi arc endpoints

Abstract

The Fermi surface as a contour of the gapless quasiparticle excitation in momentum space is studied based on a mean-field theory of the doped Mott insulator, where the underlying pseudogap phase is characterized by a two-component resonating-valence-bond (RVB) order that vanishes in the overdoping at $\delta>\delta^*$. Here the quasiparticle emerges as a ``collective'' mode and a Fermi arc is naturally present in the pseudogap regime, while a full Fermi surface is recovered at $\delta>\delta^*$. The area enclosed by the gapless quasiparticle contour still satisfies the Luttinger volume in both cases, and the ``Fermi arc'' at $\delta<\delta^*$ is actually due to a significant reduction of the spectral weight caused by a quasiparticle fractionalization in the antinodal region. The endpoints of the Fermi arcs exhibit enhanced density of states or ``hotspots'', which can further give rise to a charge-density-wave-like quasiparticle interference pattern. At the critical doping $\delta^*$, the fractionalized spin excitations become gapless and incoherent which is signaled by a divergent specific heat. At $\delta>\delta^*$, the quasiparticle excitation restores the coherence over the full Fermi surface, but the fractionalization still persists at a higher energy/temperature which may be responsible for a strange metal behavior. Different mechanisms for the Fermi arc and experimental comparisons are briefly discussed.