# Multiple gaps revealed by low temperature specific heat in the 1111-type CaFe_{0.88}Co_{0.12}AsF single crystals

## TL;DR

This study investigates the low-temperature specific heat of CaFe_{0.88}Co_{0.12}AsF single crystals, revealing multiple superconducting gaps through magnetic field dependence and detailed analysis, indicating a two-gap superconducting scenario.

## Contribution

The paper provides experimental evidence of multiple superconducting gaps in CaFe_{0.88}Co_{0.12}AsF using specific heat measurements and analysis of magnetic field effects.

## Key findings

- Observation of a specific heat jump at T_c
- Linear increase of electronic SH coefficient with magnetic field below 5 T
- Identification of a two-gap superconducting scenario with a 2:8-4:5 ratio

## Abstract

Low-temperature specific heat (SH) is measured on the 1111-type CaFe_{0.88}Co_{0.12}AsF single crystals under different magnetic fields. A clear SH jump with the height \Delta C/T|_Tc = 10.4 mJ/mol K^2 was observed at the superconducting transition temperature T_c. The electronic SH coefficient \Delta\gamma (B) increases linearly with the field below 5 T and a kink is observed around 5 T, indicating a multi-gap feature in the present system. Such a sign is also reflected in the Tc-B data. A detailed analysis shows that this behavior can be interpreted in terms of a two-gap scenario with the ratio \Delta_L=\Delta_S = 2:8-4:5.