Hole dynamics in an antiferromagnet across a deconfined quantum critical point

Abstract

We study the effects of a small density of holes, δ, on a square lattice antiferromagnet undergoing a continuous transition from a Neel state to a valence bond solid at a deconfined quantum critical point. We argue that at non-zero δ, it is likely that the critical point broadens into a non-Fermi liquid 'holon metal' phase with fractionalized excitations. The holon metal phase is flanked on both sides by liquid states with surfaces enclosing the usual Luttinger area. However the electronic quasiparticles carry distinct quantum numbers in the two liquid phases, and consequently the ratio limδ→0 AF /δ (where AF is the area of a hole pocket) has a factor of 2 discontinuity across the quantum critical point of the insulator. We demonstrate that the electronic spectrum at this transition is described by the 'boundary' critical theory of an impurity coupled to a 2+1 dimensional conformal field theory. We compute the finite temperature quantum-critical electronic spectra and show that they resemble Fermi arc spectra seen in recent photoemission experiments on the pseudogap phase of the cuprates.