title: Observation of Leggett's collective mode in a multiband MgB2 superconductor.
abstract: We report observation of Leggett's collective mode in a multiband MgB2 superconductor with Tc=39 K arising from the fluctuations in the relative phase between two superconducting condensates. The novel mode is observed by Raman spectroscopy at 9.4 meV in the fully symmetric scattering channel. The observed mode frequency is consistent with theoretical considerations based on first-principles computations.
authors.affiliation: Bell Laboratories, Alcatel-Lucent, Murray Hill, New Jersey 07974, USA. girsh@bell-labs.com
authors.forename: G
authors.initials: G
authors.lastname: Blumberg
authors.forename: A
authors.initials: A
authors.lastname: Mialitsin
authors.forename: B S
authors.initials: BS
authors.lastname: Dennis
authors.forename: M V
authors.initials: MV
authors.lastname: Klein
authors.forename: N D
authors.initials: ND
authors.lastname: Zhigadlo
authors.forename: J
authors.initials: J
authors.lastname: Karpinski