Correlation between $T_{\mathrm{c}}$ and the Pseudogap Observed in the Optical Spectra of High $T_{\mathrm{c}}$ Superconducting Cuprates

TL;DR

This study investigates the optical spectra of high-temperature cuprate superconductors, revealing a pseudogap feature that correlates with the critical temperature, suggesting a link between pseudogap phenomena and superconductivity.

Contribution

It provides experimental evidence of a correlation between the pseudogap-related conductivity peak energy and the optimal critical temperature across different cuprate materials.

Findings

Pseudogap-related conductivity suppression observed above $T_c$.

Peak energy of the conductivity spectrum is doping-independent.

Clear correlation between $T_c$ and pseudogap peak energy across cuprates.

Abstract

We studied the temperature dependences of the optical spectra for optimally and underdoped Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+z}$ single crystals. Similarly to the other cuprates' cases, a gap-like conductivity suppression was observed with reducing the temperature from above $T_{\mathrm{c}}$, creating a peak in the conductivity spectrum. The conductivity peak energy was insensitive to the doping level, namely $T_{\mathrm{c}}$, which suggests that this gap is not a superconducting gap but is related to the pseudogap. Comparing the data of various mono-, double-, and triple-layer cuprates, we found a clear correlation between the optimal $T_{\mathrm{c}}$ of each material and the pseudogap-related conductivity peak energy.