Universal optimal hole-doping concentration in single-layer high-temperature cuprate superconductors

TL;DR

This paper identifies a universal optimal hole-doping concentration in single-layer high-temperature cuprate superconductors, linking it to the maximum superconducting transition temperature and electronic energy bounds.

Contribution

It introduces the concept of two types of hole-doping concentrations, $P_{pl}$ and $P_{3D}$, and establishes a universal $P_{3D}^{opt.}$ for optimal superconductivity.

Findings

$T_c$ varies systematically with $P_{3D}$

Universal optimal $P_{3D}^{opt.}$ at 1.6 x 10^{21} cm^{-3}

Upper bound of electronic energy linked to $P_{3D}^{opt.}$

Abstract

We argue that in cuprate physics there are two types, hole content per CuO$_2$ plane ($P_{pl}$) and the corresponding hole content per unit volume ($P_{3D}$), of hole-doping concentrations for addressing physical properties that are two-dimensional (2D) and three-dimensional (3D) in nature, respectively. We find that superconducting transition temperature ($T_c$) varies systematically with $P_{3D}$ as a superconducting \textquotedblleft $dome$\textquotedblright with a universal optimal hole-doping concentration $P_{3D}^{opt.}$ = 1.6 $\times$ 10$^{21}$ cm$^{-3}$ for single-layer high temperature superconductors. We suggest that $P_{3D}^{opt.}$ determines the upper bound of the electronic energy of underdoped single-layer high-$T_c$ cuprates.