Crystal structure and superconductivity in the Ni-based ternary compound LaNiSi

Abstract

With powder-x-ray-diffraction methods, the ternary compound LaNiSi has been identified to have a LaPtSi-type crystal structure with four formula units in a unit cell of the space group I41md with dimensions a=4.181(1) Å, c=14.069(8) Å. The agreement of the transition temperature Tc=1.20∼1.26 K (10∼90 % values) measured by ac-susceptibility and heat-capacity techniques provides clear evidence of bulk superconductivity in LaNiSi. The normal-state specific-heat data can be fit to the expression Cn=γT+βT3 by a least-squares analysis, where γ=8.89 mJ/mol K2 and β=0.487 mJ/mol K4, resulting in a Debye temperature ΘD=229 K. Below Tc, the specific-heat data have a dominant low-temperature behavior of the form exp[-Δ(0)/kBT], where the order parameter 2Δ(0)=3.5kBTc. In addition, the measured heat-capacity jump ΔC at the transition point is found to be equal to 1.46γTc, implying that LaNiSi is a weakly coupled superconductor.

Source-reported materials — not catalogue approval

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