Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-$T_{\rm c}$ superconductors

TL;DR

This study uses quantum oscillations to demonstrate that the antinodal states in underdoped high-$T_c$ superconductors are gapped by a hard gap, clarifying the nature of the pseudogap phase.

Contribution

It provides direct evidence that the antinodal states are destroyed by a hard gap, distinguishing between damping and gapping scenarios in the pseudogap regime.

Findings

Quantum oscillations show an isolated small Fermi surface pocket.

Antinodal states are destroyed by a hard gap, not damping.

Results constrain theories of the pseudogap phase.

Abstract

An understanding of the missing antinodal electronic excitations in the pseudogap state is essential for uncovering the physics of the underdoped cuprate high temperature superconductors. The majority of high temperature experiments performed thus far, however, have been unable to discern whether the antinodal states are rendered unobservable due to their damping, or whether they vanish due to their gapping. Here we distinguish between these two scenarios by using quantum oscillations to examine whether the small Fermi surface pocket, found to occupy only 2% of the Brillouin zone in the underdoped cuprates, exists in isolation against a majority of completely gapped density of states spanning the antinodes, or whether it is thermodynamically coupled to a background of ungapped antinodal states. We find that quantum oscillations associated with the small Fermi surface pocket exhibit a signature sawtooth waveform characteristic of an isolated two-dimensional Fermi surface pocket. This finding reveals that the antinodal states are destroyed by a hard gap that extends over the majority of the Brillouin zone, placing strong constraints on a drastic underlying origin of quasiparticle disappearance over almost the entire Brillouin zone in the pseudogap regime.