Possible Microscopic Doping Mechanism in Tl-2201

TL;DR

This paper investigates a microscopic doping mechanism in Tl-2201, proposing that interstitial oxygens are attracted to copper substitutions on thallium sites, which contributes holes and influences the material's doping level.

Contribution

It introduces a new microscopic doping mechanism involving interstitial oxygens and copper substitutions, supported by X-ray absorption spectroscopy data.

Findings

Interstitial oxygens are attracted to copper substitutions.

Copper substitutions contribute intrinsic holes to the material.

Typically only one hole is promoted to the plane rather than two.

Abstract

X-ray absorption spectroscopy on oxygen-annealed, self-flux-grown single crystals of Tl-2201 suggests a microscopic doping mechanism whereby interstitial oxygens are attracted to copper substituted on the thallium site, contributing holes to both the planes and to these coppers, and typically promoting only one hole to the plane rather than two. These copper substituents would provide an intrinsic hole doping. The evidence for this is discussed, along with an alternative interpretation.