High-pressure evolution of the specific heat of a strongly underdoped Ba(Fe0.963Co0.037)As2 iron-based superconductor

Y. Zheng; Y. Wang; F. Hardy; A. E. Böhmer; T. Wolf; C. Meingast; R. Lortz

doi:10.1103/PhysRevB.89.054514

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High-pressure evolution of the specific heat of a strongly underdoped Ba(Fe0.963Co0.037)As2 iron-based superconductor

Y. Zheng, Y. Wang, F. Hardy, A. E. Böhmer, T. Wolf, C. Meingast, R. Lortz

DOI 10.1103/PhysRevB.89.054514 · Physical Review B

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Abstract

We report on 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 specific heat are sharper than those 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 those in optimally Co-doped samples at ambient pressure, which we attribute to a weak pair-breaking effect of the Co ions.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Ba(Fe0.963Co0.037)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.7	Pressure unresolved	onset
Ba(Fe0.963Co0.037)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6	Pressure unresolved	zero_resistance
Ba(Fe0.963Co0.037)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	18	0.3 GPa	midpoint
Ba(Fe0.963Co0.037)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	25	2.3 GPa	zero_resistance
Ba(Fe0.963Co0.037)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	30	2.3 GPa	onset
Ba(Fe0.963Co0.037)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22	4.4 GPa	unknown
Ba(Fe0.965Co0.035)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure unresolved	unknown
Ba(Fe0.96Co0.04)As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.2	Pressure unresolved	onset