Superconducting specific-heat jump ΔCel∝Tcβ(β≈2) for K1−xNaxFe2As2

V. Grinenko; D. V. Efremov; S.-L. Drechsler; S. Aswartham; D. Gruner; M. Roslova; I. Morozov; K. Nenkov; S. Wurmehl; A. U. B. Wolter; B. Holzapfel; B. Büchner

doi:10.1103/PhysRevB.89.060504

Superconducting specific-heat jump ΔCel∝Tcβ(β≈2) for K1−xNaxFe2As2

V. Grinenko, D. V. Efremov, S.-L. Drechsler, S. Aswartham, D. Gruner, M. Roslova, I. Morozov, K. Nenkov, S. Wurmehl, A. U. B. Wolter, B. Holzapfel, B. Büchner

DOI 10.1103/PhysRevB.89.060504 · Physical Review B

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Abstract

We present a systematic study of the electronic specific-heat jump (ΔCel) at the superconducting transition temperature Tc of K1−xNaxFe2As2. Both Tc and ΔCel monotonously decrease with increasing x. The specific heat jump scales approximately with a power law, ΔCel∝Tcβ, with β≈2 determined by the impurity scattering rate, in contrast to most iron-pnictide superconductors, where the remarkable Bud'ko-Ni-Canfield (BNC) scaling ΔCel∝T3 has been found. Both the T dependence of Cel(T) in the superconducting state and the nearly quadratic scaling of ΔCel at Tc are well described by the Eliashberg theory for a two-band d-wave superconductor with weak pair breaking due to nonmagnetic impurities. The disorder induced by the Na substitution significantly suppresses the small gaps, leading to gapless states in the slightly disordered superconductor, which results in a large observed residual Sommerfeld coefficient in the superconducting state for x>0.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
K1-xNaxFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.44	Pressure not reported	onset
K1-xNaxFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.44	Pressure not reported	onset
K1-xNaxFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.44	Pressure not reported	onset
KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.44	Pressure not reported	unknown
RbFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
CsFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
LiFeAs Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
LiFeP Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown