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Register a new userPossible evidence for two-gap superconductivity in TiSe_2Cu_x
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We report a comprehensive TF-muSR study of TiSe_2Cu_2. The magnetic penetration depth was found to saturate at low temperature as expected in an s-wave SC. As x is increased we find that the superfluid density increases and the size of the superconducting gap, calculated from the temperature dependence of the superfluid density, is approaching the BCS value. However, for low values of x, the gap is smaller than the weak-coupling BCS prediction suggesting that two superconducting gaps are present in the sample.
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We study the superconducting properties of the non-centrosymmetric compound LaNiC$_2$ by measuring the London penetration depth $Delta lambda (T)$, the specific heat $C(T,B)$ and the electrical resistivity $rho (T,B)$. Both $Deltalambda (T)$ and the electronic specific heat $C_e(T)$ exhibit exponential behavior at low temperatures and can be described in terms of a phenomenological two-gap BCS model. The residual Sommerfeld coefficient in the superconducting state, $gamma_0(B)$, shows a fast increase at low fields and then an eventual saturation with increasing magnetic field. A pronounced upturn curvature is observed in the upper critical field $B_{c2}(T)$ near $T_{c}$. All the experimental observations support the existence of two-gap superconductivity in LaNiC$_2$.
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