title: Evidence for fully gapped strong coupling s-wave superconductivity in Bi4O4S3.
abstract: We report on the superconducting gap and pairing symmetry in the layered superconductor Bi4O4S3. The measurement of temperature dependence of magnetic penetration depth was carried out using the tunnel diode oscillator technique. It is observed that Bi4O4S3 is a conventional s-wave type superconductor with a fully developed gap. The zero-temperature value of the superconducting energy gap Δ0 was found to be 1.54 meV, corresponding to the ratio 2Δ0/k(B)T(c) = 7.2 which is much higher than the BCS value of 3.53. In the superconducting range, superfluid density is very well described by the single gap s-wave model.
authors.affiliation: School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
authors.lastname: Shruti
authors.forename: P
authors.initials: P
authors.lastname: Srivastava
authors.forename: S
authors.initials: S
authors.lastname: Patnaik