Observation of Leggett's collective mode in a multiband MgB(2) superconductor
30 November 2007
We report observation of Leggett's collective mode in a multiband MgB(2) superconductor with T(c)=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.