title: Experimental evidence of s-wave superconductivity in bulk CaC6.
abstract: The temperature dependence of the in-plane magnetic penetration depth, lambda(ab)(T), has been measured in a c-axis oriented polycrystalline CaC(6) bulk sample using a high-resolution mutual inductance technique. A clear exponential behavior of lambda(ab)(T) has been observed at low temperatures, strongly suggesting isotropic s-wave pairing. Data fit using the standard BCS theory yields lambda(ab)(0) = (720 +/- 80) A and delta(0) = (1.79 +/- 0.08) meV. The ratio 2delta(0)/k(B)T(c) = (3.6 +/- 0.2) gives indication for a weakly coupled superconductor.
authors.affiliation: CNR-INFM Coherentia and Department of Physics, University of Naples, Federico II, I-80125, Napoli, Italy. gianrico.lamura@na.infn.it
authors.forename: G
authors.initials: G
authors.lastname: Lamura
authors.forename: M
authors.initials: M
authors.lastname: Aurino
authors.forename: G
authors.initials: G
authors.lastname: Cifariello
authors.forename: E
authors.initials: E
authors.lastname: Di Gennaro
authors.forename: A
authors.initials: A
authors.lastname: Andreone
authors.forename: N
authors.initials: N
authors.lastname: Emery
authors.forename: C
authors.initials: C
authors.lastname: Hérold
authors.forename: J-F
authors.initials: JF
authors.lastname: Marêché
authors.forename: P
authors.initials: P
authors.lastname: Lagrange