x_opt and x_c in Cuprate Superconductors

TL;DR

This paper explores the mesoscale organization of bond-like RVB arrays in cuprate superconductors, revealing how different arrangements influence optimal doping levels, T_c, and pseudogap behavior.

Contribution

It uncovers the interrelation of characteristic doping levels with mesoscale RVB arrangements and their impact on superconducting properties.

Findings

Columnar organization maximizes T_c but reduces superfluid stiffness.

Zigzag organization maximizes superfluid stiffness and closes the pseudogap.

Mesoscale RVB arrangements transform between x_opt and x_c with weak overdoping.

Abstract

The characteristic hole concentrations x_opt = 0.16 and x_c = 0.19 in the under- to overdoped transition regime of cuprate superconductors are shown to be intimately interrelated by mesoscale organization of bond-like RVB arrays extending over 3 x 4 copper sites and comprising 2 holes spaced by 3a_0. Columnar organization maximizes T_c but reduces the superfluid stiffness, while zigzag (tweedy) organization maximizes the superfluid stiffness at reduced T_c. The latter goes hand in hand with the closure of the pseudogap. Columnar and zigzag mesoscale organizations of the bond-like RVB arrays are displacively transformed in each other between x_opt and x_c by weak overdoping.