Superconducting and normal-state properties of APd2As2 (A = Ca, Sr, Ba) single crystals

V. K. Anand; H. Kim; M. A. Tanatar; R. Prozorov; D. C. Johnston

doi:10.1103/PhysRevB.87.224510

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Superconducting and normal-state properties of APd2As2 (A = Ca, Sr, Ba) single crystals

V. K. Anand, H. Kim, M. A. Tanatar, R. Prozorov, D. C. Johnston

DOI 10.1103/PhysRevB.87.224510 · Physical Review B

T1

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Abstract

The synthesis and crystallography, magnetic susceptibility χ, magnetization M, specific heat Cp, in-plane electrical resistivity ρ, and in-plane magnetic penetration depth measurements are reported for single crystals of APd2As2 (A = Ca, Sr, Ba) versus temperature T and magnetic field H. The crystals were grown using PdAs self-flux. CaPd2As2 and SrPd2As2 crystallize in a collapsed body-centered tetragonal ThCr2Si2-type structure (I4/mmm), whereas BaPd2As2 crystallizes in the primitive tetragonal CeMg2Si2-type structure (P4/mmm), in agreement with literature data. The ρ(T) data exhibit metallic behavior for all three compounds. Bulk superconductivity is reported for CaPd2As2 and SrPd2As2 below Tc=1.27 and 0.92 K, respectively, whereas only a trace of superconductivity is found in BaPd2As2. No other phase transitions were observed. The χ(T) and M(H) data reveal anisotropic diamagnetism in the normal state, with χc>χab for CaPd2As2 and BaPd2As2, and χc<χab for SrPd2As2. The normal and superconducting state data indicate that CaPd2As2 and SrPd2As2 are conventional type-II nodeless s-wave electron-phonon superconductors. The electronic superconducting state heat capacity data for CaPd2As2, which has an extremely sharp heat capacity jump at Tc, are analyzed using our recent elaboration of the α-model of the BCS theory of superconductivity, which indicates that the s-wave gap in this compound is anisotropic in momentum space.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
CaPd2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.27	Pressure not reported	unknown
CaPd2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.27	Pressure not reported	unknown
SrPd2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.92	Pressure not reported	unknown
SrPd2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.92	Pressure not reported	unknown
BaPd2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2	Pressure not reported	onset
SrPd2Ge2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3	Pressure not reported	unknown