Superconducting Puddles and "Colossal'' Effects in Underdoped Cuprates

TL;DR

This paper explores how nanoscale superconducting puddles and glassy states in underdoped cuprates can lead to colossal effects, where weak perturbations rapidly induce superconductivity, challenging the universality of the AF to SC transition.

Contribution

It introduces phenomenological models showing diverse behaviors in underdoped cuprates, including glassy states with superconducting puddles and potential colossal effects.

Findings

Glassy states with nanoscale SC puddles can cause colossal effects.

The AF to SC transition is not universal in cuprates.

Weak perturbations can rapidly induce superconductivity in certain conditions.

Abstract

Phenomenological models for the antiferromagnetic (AF) vs. d-wave superconductivity competition in cuprates are studied using conventional Monte Carlo techniques. The analysis suggests that cuprates may show a variety of different behaviors in the very underdoped regime: local coexistence or first-order transitions among the competing orders, stripes, or glassy states with nanoscale superconducting (SC) puddles. The transition from AF to SC does not seem universal. In particular, the glassy state leads to the possibility of "colossal'' effects in some cuprates, analog of those in manganites. Under suitable conditions, non-superconducting Cu-oxides could rapidly become superconducting by the influence of weak perturbations that align the randomly oriented phases of the SC puddles in the mixed state. Consequences of these ideas for thin-film and photoemission experiments are discussed.