Two-gap superconducting states of LaRu[formula omitted]Si[formula omitted]

Abstract

We synthesize high-quality LaRu3Si2 (Tc= 7.5 K) polycrystalline sample and report the superconducting gap anisotropy relative to the temperature dependence of μ0Hc2 and Cel/γTc below Tc. The μ0Hc2 satisfies T-linear dependence until it approaches a low temperature region (T≤0.25Tc), and this behavior may not agree with the WHH theory. Based on T-linear fitting, the μ0Hc2(0) is estimated to be 10.2 T. The Cel/γTc below Tc cannot be expressed by a simple exponential fit. It is considered that although a larger gap (2Δ1/kBTc=3.63) opens at 3 K ≤T≤Tc, low-lying quasiparticle excitations at T≤ 3 K are dominated by a smaller gap (2Δ2/kBTc=2.62). Our experimental results indicate the feasibility of a two-gap superconducting state of LaRu3Si2.