Observation of Multiple Superconducting Gaps in the Infrared Reflectivity Spectra of Ba(Fe0.9Co0.1)2As2

TL;DR

Infrared reflectivity measurements of Ba(Fe0.9Co0.1)2As2 reveal multiple superconducting gaps and suggest s+/- or s+/+ symmetry of the order parameter, advancing understanding of iron-based high-temperature superconductors.

Contribution

First observation of multiple superconducting gaps in Ba(Fe0.9Co0.1)2As2 using infrared reflectivity, indicating complex gap structure in iron-based superconductors.

Findings

Reflectivity close to unity below 2Delta/h indicating superconducting gaps.

Evidence for s+/- or s+/+ symmetry of the order parameter.

Multiple gaps open at temperatures below Tc.

Abstract

The results of infrared reflectivity measurements for the iron-based high-temperature superconductor Ba(Fe0.9Co0.1)2As2 are reported. The reflectivity is found to be close to unity at frequencies w lower than 2Delta/h (2Delta is the superconducting gap and h is Planck's constant). This is evidence for the s+/- or s+/+ symmetry of the superconducting order parameter in the studied compound. The infrared reflectivity spectra of Ba(Fe0.9Co0.1)2As2 manifest opening of several superconducting gaps at temperatures lower than critical Tc.