Thermodynamic Properties and Pressure Effect on the Superconductivity in CaAlSi and SrAlSi

Abstract

Superconductivity in the C32 compounds CaAlSi and SrAlSi is investigated by heat capacity (Cp) measurements as well as high-pressure ac-susceptibility experiments. The heat capacity in the superconducting state is well explained by the BCS theory in the weak-coupling limit. The jump of Cp at the superconducting transition (compared to the normal state electronic heat capacity) is 1.62 and 1.21 for CaAlSi and SrAlSi, respectively, and agrees well with the BCS value of 1.43. 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 (+0.026 GPa-1) but negative in SrAlSi (-0.024 GPa-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.

arXiv commentRevised manuscript, Fig. 1 replaced, Phys. Rev. B in press

References in corpus (4)

• Specific Heat of Mg ^{11}B_2
• High Pressure Study on MgB2
• Superconductivity in the C32 Intermetallic Compounds AAl(2-x)Si(x), with A=Ca and Sr, and 0.6<x<1.2
• Superconductivity of MI(MII0.5, Si0.5)2 (MI=Sr and Ba, MII=Al and Ga), ternary silicides with the AlB2-type structure

Cited by in corpus (12)

• Magnetic Penetration Depth in Unconventional Superconductors
• Effect of Pressure on Superconducting Ca-intercalated Graphite CaC${}_6$
• Electrons and phonons in the ternary alloy CaAl${}_{2-x}$Si${}_x$} as a function of composition
• High Pressure Effects on Superconductivity
• Anisotropic s-wave superconductivity in single crystals CaAlSi from penetration depth measurements
• Pressure effects on the superconducting transition in nH-CaAlSi
• Two-gap to Single-gap Superconducting Transition on a Honeycomb Lattice in Ca${}_{1-x}$Sr${}_x$AlSi
• Engineering of a Layered Ferromagnet via Graphitization: An Overlooked Polymorph of GdAlSi
• First-Order Reorientation of the Flux-Line Lattice in CaAlSi
• Structural Phase Transition and Superconductivity in 2H-BaGaGe with Buckled Honeycomb Layers
• On the origin of unusual transport properties observed in densely packed polycrystalline CaAl_{2}
• Subtle Structural Anomaly under Compression in Line-Nodal CaSb${}_2$