Pairing and Phase Coherence in High Temperature Superconductors

TL;DR

This paper proposes a model where mobile holes in high-temperature superconductors form stripe-like structures that induce a pseudogap and facilitate pairing through a proximity effect, leading to superconductivity with unique phase coherence properties.

Contribution

It introduces a novel mechanism of pairing and phase coherence in high-temperature superconductors based on stripe fluctuations and magnetic proximity effects.

Findings

Stripe formation induces a pseudogap in the Mott insulator.

Pair hopping between stripes leads to superconducting pairing.

Josephson coupling causes a transition to a phase-coherent superconducting state.

Abstract

Mobile holes in an antiferromagnetic insulator form a slowly fluctuating array of quasi one-dimensional metallic stripes, which induce a spin gap or pseudogap in the intervening Mott-insulating regions. The mobile holes on an individual stripe acquire a spin gap via pair hopping between the stripe and its environment; i.e. via a magnetic analog of the usual superconducting proximity effect. This process is the analog of pairing in conventional superconductors. At non-vanishing stripe densities, Josephson coupling between stripes produces a dimensional crossover to a state with long-range superconducting phase coherence. In contrast to conventional superconductors, the superconducting state is characterised by a high density of (spin) pairs, but the phase stiffness, which is determined by the density and mobility of holes on the stripes, is very low.