Double pair breaking peak in Raman scattering spectra of triple layer cuprate Bi2223

TL;DR

This study uses Raman scattering to investigate the superconducting gaps in triple-layer cuprate Bi2223 across various doping levels, revealing a double pair-breaking peak linked to different CuO2 planes and suggesting interlayer interactions.

Contribution

It reports the first observation of a double pair-breaking peak in Raman spectra of Bi2223, linking it to distinct gaps in outer and inner CuO2 planes and analyzing doping dependence.

Findings

Double pair-breaking peak observed in Bi2223 Raman spectra.

OP and IP peaks align on a single doping-dependent line.

Gap energy does not scale with Tc, indicating strong interactions.

Abstract

We report the Raman scattering measurements on the triple layer Bi2Sr2Ca2Cu3O10 (Bi2223) crystals of four different doping levels from slightly overdoped to strongly underdoped regimes. We observed a double pair-breaking peak in the antinodal B1g configuration that we attribute to the two antinodal gaps opening on the outer and inner CuO2-plane (OP and IP) band, respectively. The doping dependence of the pair-breaking peak energy was investigated. Considering the difference in doping level between the IP and OP, all the B1g pair-breaking peak energies for OP and IP were found to align on a single line as a function of doping, which is consistent with the previous results on the double and mono-layer cuprates. Within our experimental accuracy the IP and OP peaks start to appear almost at the same temperature. These findings suggest some sort of interaction between the layers. The observed gap energy is very large, not scaling with Tc.