Bose-Einstein to BCS Crossover Picture for High-T_c Cuprates

TL;DR

This paper proposes a unified framework for high-T_c cuprates that describes their evolution from Bose-Einstein condensation to BCS superconductivity, based on universal correlations and pseudogap behavior.

Contribution

It introduces a comprehensive picture connecting BEC and BCS regimes in cuprates, emphasizing the role of superfluid density and phase separation.

Findings

Overdoped and Zn-substituted cuprates show reduced superfluid density due to phase separation.

Scaling of T_c with superfluid density highlights Bose condensation importance.

Universal T_c and n_s/m* correlations support the BEC-BCS crossover model.

Abstract

Combining (1) the universal correlations between $T_{c}$ and $n_{s}/m^{*}$ (superconducting carrier density / effective mass) and (2) the pseudo-gap behavior in the underdoped region, we obtain a picture to describe superconductivity in cuprate systems in evolution from Bose-Einstein to BCS condensation. Overdoped and Zn-substituted cuprate systems show signatures of reduced superfluid density in a microscopic phase separation. Scaling of $T_{c}$ to the superfluid volume density $n_{s}$ in all these cases indicate importance of Bose condensation.