Planar Cu and O hole densities in high-Tc cuprates determined with NMR

TL;DR

This paper uses NMR hyperfine interactions to measure hole densities at Cu and O sites in high-Tc cuprates, revealing how doping affects hole distribution and phase diagrams.

Contribution

It introduces a method to determine hole densities at Cu and O sites in cuprates using NMR quadrupole splitting, providing new insights into doping effects.

Findings

All doped holes in La2-xSrxCuO4 reside mainly at O sites.

Doped holes in YBa2Cu3O6+y are distributed between Cu and O sites depending on oxygen content.

The phase diagram based on NMR data offers new understanding of doping effects in cuprates.

Abstract

The electric hyperfine interaction observable in atomic spectroscopy for O and Cu ions in various configurations is used to analyze the quadrupole splitting of O and Cu nuclear magnetic resonance (NMR) in La2-xSrxCuO4 and YBa2Cu3O6+y and to determine the hole densities at both sites as a function of doping. It is found that in La2-xSrxCuO4 all doped holes (x) reside in the Cu-O plane but almost exclusively at O. For YBa2Cu3O6+y and y<0.6 doped holes are found at planar Cu as well as O. For y>0.6 further doping increases the hole content only for planar O. The phase diagram based on NMR data is presented. Further implications from the Cu A and B site in La2-xSrxCuO4 and the two planar O sites in YBa2Cu3O6+y and consequences for the phase diagram are discussed.