Thermodynamic properties and pressure effect on the superconductivity in CaAlSi and SrAlSi
B. Lorenz, J. Cmaidalka, R. L. Meng, C. W. Chu
DOI 10.1103/PhysRevB.68.014512 · Physical Review B
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Abstract
Superconductivity in the C32 compounds CaAlSi and SrAlSi is investigated by heat capacity measurements as well as high-pressure ac-susceptibility experiments. The heat capacity in the superconducting state is well explained by the BCS theory for weak (SrAlSi) and enhanced coupling strength (CaAlSi). The magnitudes of the superconducting gaps are estimated as 2.7 meV (CaAlSi) and 1.4 meV (SrAlSi). The pressure effect on the superconducting transition temperature, dlnTc/dp, is positive in CaAlSi (+0.026GPa−1) but negative in SrAlSi (−0.024GPa−1). The opposite sign of the pressure coefficients of Tc indicates distinct differences in the electronic structure and the density of states at the Fermi energy of the two compounds in agreement with recent band structure calculations.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| CaAlSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 7.7 | Pressure unresolved | midpoint |
| SrAlSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 4.9 | Pressure unresolved | midpoint |
| CaAlSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 7.9 | Pressure unresolved | onset |
| SrAlSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 5 | Pressure unresolved | onset |
| CaSi2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 14 | 14 GPa | unknown |
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