Observing the Superconducting State of HgBa2Ca2Cu3O8+d Cuprate by Electronic Raman Scattering

TL;DR

This study uses electronic Raman scattering to investigate the superconducting state of HgBa2Ca2Cu3O8+d, revealing a strong coupling d-wave pairing gap with complex spectral features and interconnected quasiparticle dynamics.

Contribution

It provides new insights into the pairing gap magnitude, spectral structure, and c-axis quasiparticle dynamics in HgBa2Ca2Cu3O8+d, a high-temperature cuprate superconductor.

Findings

The antinodal pairing gap is higher (14 kBTc) than in other cuprates.

The pairing-gap feature shows a complex peak-dip-hump structure.

The pairing gap is detected for both (ab) plane and c-axis polarizations.

Abstract

Electronic Raman scattering with in and out of (ab) plane polarizations have been performed on HgBa2Ca2Cu3O8+d in a slightly underdoped single crystal with a critical temperature Tc=122 K. We find that the d-wave pairing gap at the antinodes is higher in energy (14 kBTc) than in other cuprates and that it varies very slowly up to Tc. This hints at a strong coupling nature of the pairing mechanism. Interestingly, we reveal that the pairing-gap feature in the Raman response displays a complex peak-dip-hump structure, in a fashion reminiscent of what observed by angle resolved photo-emission spectroscopy in Bi2Sr2CaCu2O8+d (Bi-2212). We detect two other distinct superconducting peaks at 5kBTc and 7kBTc when probing respectively around the nodes and on the whole Fermi surface. Finally we establish that the pairing gap at the antinodes is detected both for (ab) plane and for c-axis light polarizations. This shows that the quasiparticle dynamics along the c-axis is intimately connected to the antinodal one in the (ab) plane.