Intrinsic Impurity in the High Temperature Superconductor Bi_2Sr_2CaCu_2O$_{8+\delta}$

TL;DR

This study uses ^17O NMR to investigate intrinsic impurity effects in Bi-2212 high-temperature superconductor, revealing magnetically broadened inhomogeneous magnetism linked to oxygen doping that persists into the superconducting state.

Contribution

It provides the first detailed NMR analysis of intrinsic impurity effects in Bi-2212, showing how oxygen doping causes persistent inhomogeneous magnetism.

Findings

NMR linewidth broadening follows a Curie law with temperature.

Magnetic inhomogeneity is intrinsic to oxygen doping.

Inhomogeneous magnetism persists into the superconducting state.

Abstract

The {}^{17}O NMR spectra of Bi_2Sr_2CaCu_2O$_{8+\delta}$ (Bi-2212) single crystals were measured in the temperature range from 4 K to 200 K and magnetic fields from 3 to 29 T, reported here principally at 8 T. The NMR linewidth of the oxygen in the CuO_{2} plane was found to be magnetically broadened with the temperature dependence of a Curie law where the Curie coefficient decreases with increased doping. This inhomogeneous magnetism is an impurity effect intrinsic to oxygen doping and persists unmodified into the superconducting state.