Effect of Sr substitution on superconductivity in Hg2(Ba1-ySry)2YCu2O8-d (part2): bond valence sum approach of the hole distribution

TL;DR

This study investigates how Sr substitution affects superconductivity in Hg2(Ba1-ySry)2YCu2O8-d by analyzing hole distribution and charge transfer mechanisms, revealing a Tc increase from 0 to 42 K with Sr content.

Contribution

It introduces a bond valence sum approach to analyze hole doping and charge transfer in Sr-substituted Hg-based cuprates, explaining Tc enhancement.

Findings

Tc increases from 0 K to 42 K with Sr substitution.

Charge transfer to CuO2 plane occurs via two doping channels.

Bond valence sum analysis elucidates hole distribution mechanisms.

Abstract

The effects of Sr substitution on superconductivity, and more particulary the changes induced in the hole doping mechanism, were investigated in Hg2(Ba1-ySry)2YCu2O8-d by a "bond valence sum" analysis with Sr content from y = 0.0 to y = 1.0. A comparison with CuBa2YCu2O7-d and Cu2Ba2YCu2O8 systems suggests a possible explanation of the Tc enhancement from 0 K for y = 0.0 to 42 K for y = 1.0. The charge distribution among atoms of the unit cell was determined from the refined structure, for y = 0.0 to 1.0. It shows a charge transfer to the superconducting CuO2 plane via two doping channels pi(1) and pi(2), i.e. through O2(apical)-Cu and Ba/Sr-O1 bonds respectively.