High-Pressure Evolution of the Specific Heat of a Strongly Underdoped Ba(Fe0.963Co0.037)As2 Iron-Based Superconductor

TL;DR

This study investigates how high pressure affects the specific heat and superconducting properties of a strongly underdoped Ba(Fe0.963Co0.037)As2 superconductor, revealing enhanced bulk superconductivity and phase diagram insights.

Contribution

First thermodynamic study of pressure effects on specific heat in strongly underdoped BaFe2As2 superconductor, highlighting bulk superconductivity and phase diagram details.

Findings

Large specific-heat anomalies at Tc confirm bulk superconductivity.

Pressure increases Tc and condensation energy beyond ambient doping levels.

Sharper specific heat transitions than resistivity measurements.

Abstract

We report specific-heat experiments under the influence of high pressure on a strongly underdoped Co-substituted BaFe2As2 single crystal. This allows us to study the phase diagram of this iron pnictide superconductor with a bulk thermodynamic method and pressure as a clean control parameter. The data show large specific-heat anomalies at the superconducting transition temperature, which proves the bulk nature of pressure-induced superconductivity. The transitions in the specific heat are sharper than in resistivity, which demonstrates the necessity of employing bulk thermodynamic methods to explore the exact phase diagram of pressure-induced Fe-based superconductors. The Tc at optimal pressure and the superconducting condensation energy are found to be larger than in optimally Co-doped samples at ambient pressure, which we attribute to a weak pair breaking effect of the Co ions.