Superconductivity in the ternary nickel silicide Lu₂Ni₃Si₅

Abstract

The synthesis and results of electrical-resistivity (1.5-300 K), ac-magnetic-susceptibility (1.5-5 K), and specific-heat (1.7-30 K) measurements are reported on a ternary rare-earth-nickel-silicide compound Lu₂Ni₃Si₅. The compound is found to be superconducting below 2.1 K. The magnetic-susceptibility measurements show the onset of diamagnetism at 2.1 K and the resistivity goes to zero at 2.0 K with the same onset temperature. The resistivity above the transition temperature shows a metallic behavior. A deviation from linear resistivity at high temperatures implies a short mean free path. The heat capacity shows a jump with a peak at 1.9 K, which indicates bulk superconducting ordering in this sample. The estimated value for γ(=C_p/T as T→0) is 5.8 mJ/Lu molK² and ΔC_p/γT_c is 1.1, which is lower than the BCS value of 1.43. From these results, we conclude that Lu₂Ni₃Si₅ is a weak-coupling BCS superconductor.