Temperature dependence of the superconducting gap anisotropy in Bi$_{2}$Sr$_{2}$Ca$_{1}$Cu$_{2}$O$_{8+x}$

TL;DR

This study provides detailed momentum-resolved data on how the superconducting gap anisotropy in Bi2Sr2Ca1Cu2O8+x varies with temperature, revealing an unusual increase in anisotropy as temperature rises.

Contribution

It presents the first detailed temperature-dependent, momentum-resolved measurements of the superconducting gap in Bi2Sr2Ca1Cu2O8+x, highlighting its increasing anisotropy with temperature.

Findings

Gap anisotropy increases with temperature.

Superconducting gap along Γ-X diminishes to zero at higher temperatures.

Gap along Γ- M remains nearly full at those temperatures.

Abstract

We present the first detailed data of the momentum-resolved, temperature dependence of the superconducting gap of $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$, complemented by similar data on the intensity of the photoemission superconducting condensate spectral area. The gap anisotropy between the $\Gamma-\bar{M}$ and $\Gamma-X$ directions increases markedly with increasing temperature, contrary to what happens for conventional anisotropic-gap superconductors such as lead. Specifically, the size of the superconducting gap along the $\Gamma-X$ direction decreases to values indistinguishable from zero at temperatures for which the gap retains virtually full value along the $\Gamma-\bar{M}$ direction.