Muon spin rotation study of the magnetic penetration depth in the intercalated graphite superconductorCaC6

Abstract

We report temperature-and magnetic field-dependent bulk muon spin rotation measurements in a c-axis-oriented superconductor CaC 6 in the mixed state. Using both a simple second-moment analysis and the more precise analytical Ginzburg-Landau model, we obtained a field-independent in-plane magnetic penetration depth ab ͑0͒ =72͑3͒ nm. The temperature dependencies of the normalized muon spin relaxation rate and of the normalized superfluid density result to be identical and both are well represented by the clean limit BCS model with 2⌬ / k B T c = 3.6͑1͒, suggesting that CaC 6 is a fully gapped BCS superconductor in the clean limit regime.

Muon Spin Rotation Study of the Intercalated Graphite Superconductor CaC6 at Low Temperatures

“…All three scenarios describe the observed temperature dependence of the superfluid density. For a direct comparison with [12], we omitted the values of ρ s (T ) below 2 K. In this case, the single s-wave gap fit yields ρ s (0) = 91.6(9) µm −2 , 0 = 0.84(1) meV, T c = 6.75(2) K, and 2 0 /k B T c = 2.90 (5). The values presented in [12] are: ρ s (0) = 85.1(3) µm −2 , 0 = 0.868(5) meV, and 2 0 /k B T c = 3.6(1).…”

“…For a direct comparison with [12], we omitted the values of ρ s (T ) below 2 K. In this case, the single s-wave gap fit yields ρ s (0) = 91.6(9) µm −2 , 0 = 0.84(1) meV, T c = 6.75(2) K, and 2 0 /k B T c = 2.90 (5). The values presented in [12] are: ρ s (0) = 85.1(3) µm −2 , 0 = 0.868(5) meV, and 2 0 /k B T c = 3.6(1). The higher applied magnetic field (120 mT in [12]) may account for the differences.…”

“…The values presented in [12] are: ρ s (0) = 85.1(3) µm −2 , 0 = 0.868(5) meV, and 2 0 /k B T c = 3.6(1). The higher applied magnetic field (120 mT in [12]) may account for the differences. Here, one should point out that our low temperature data are essential to determine the zero temperature values of ρ s and .…”

“…We found that the upper critical field anisotropy γ H = H ab c2 /H c c2 increases with decreasing temperature. From magnetic field dependent μSR experiments, the absolute value of the in-plane magnetic penetration depth was determined to be λ ab 78(3) nm, in agreement with previously reported values [7,12]. Furthermore, low temperature μSR experiments were performed in order to map the whole temperature dependence of the superfluid density ρ s (T ).…”

Overview on the intercalation of gold into graphite

“…Then many other binary compounds with alkali metals [2,3], alkaline earth elements [4] and some lanthanides [5][6][7] have been synthesized. Among these compounds, some have revealed remarkable physical and chemical properties [8][9][10][11][12][13] so that some of them lead to applications in everyday life [14,15].…”