The Pairing Mechanism in HTSC investigated by Electronic Raman Scattering

TL;DR

This study uses electronic Raman scattering to analyze the symmetry and doping dependence of the energy gap in Bi2Sr2CaCu2O8+delta, revealing a d-wave symmetry and doping-related variations consistent with paramagnon coupling theories.

Contribution

It provides experimental evidence for d_x^2-y^2-wave symmetry of the energy gap across doping levels in high-temperature superconductors.

Findings

Energy gap symmetry is consistent with d_x^2-y^2-wave in both under- and overdoped regimes.

The gap ratio 2Delta_max/k_BT_c varies with doping and temperature as predicted by paramagnon coupling theories.

Doping affects the temperature dependence of the energy gap in high-Tc superconductors.

Abstract

By means of electronic Raman scattering we investigated the symmetry of the energy gap Delta(k), its temperature dependence and its variation with doping of well characterized Bi2Sr2CaCu2O8+delta single crystals. The oxygen content delta was varied between the under- and the overdoped regime by subsequently annealing the same single crystal in Ar and O2, respectively. The symmetry analysis of the polarized electronic Raman scattering is consistent with a d_x^2-y^2-wave symmetry of the energy gap in both regimes. The gap ratio 2Delta_max/k_BT_c and its temperature dependence changes with doping similar to predictions of theories based on paramagnon coupling.