Magic doping: From the localized hole-pair to the checkerboard patterns

TL;DR

This paper presents a real-space theory explaining the emergence of checkerboard phases and the specific 'magic' doping levels in hole-doped cuprate superconductors, linking localized pairs to observed patterns and broken symmetries.

Contribution

It introduces a theoretical framework that naturally accounts for magic doping fractions and checkerboard patterns, providing insights into the mechanisms of high-temperature superconductivity.

Findings

Identifies seven 'magic numbers' corresponding to specific checkerboard patterns.

Explains the origin of symmetry breaking within copper-oxide units.

Provides a unified understanding of non-superconducting phases in cuprates.

Abstract

Intensive experiments have revealed that the superconductivity of the hole-doped cuprates can be strongly suppressed at the so-called magic doping fractions. Despite great research efforts, the origin of the `magic doping' remains mysterious. Recently, we have developed a real-space theory of high-temperature superconductivity which reveals the intrinsic relationship between the localized Cooper pair and the localized hole pair (arXiv:1007.3536). Here we report that the theory can naturally explain the emergence of non-superconducting checkerboard phases and the magic doping problem in hole-doped cuprate superconductors. It clearly shows that there exist only seven `magic numbers' in the cuprate family at $x=$1/18, 1/16, 2/25, 1/9, 1/8, 2/9 and 1/4 with 6a*6a, 4a*4a, 5a*5a, 3a*3a, 4a*4a, 3a*3a and 2a*2a checkerboard patterns, respectively. Moreover, our framework leads directly to a satisfactory explanation of the most recent discovery [M. J. Lawler, et al. Nature 466, 347 (2010)] of the symmetries broken within each copper-oxide unit in hole-doped cuprate superconductors. These findings may shed new light on the mechanism of superconductivity.