2003/04/30 by B. B. Jin, Biao Jin, T. Dahm +9
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.91.127006
published as Physical Review Letters, Vol. 91, 127006(2003) · 10 pages, 4 figures, to be published in Phys. Rev. Lett
arxiv created 2003/08/07 · openalex publication_date 2003/09/19 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The temperature dependence of the real part of the microwave complex conductivity at 17.9 GHz obtained from surface impedance measurements of two c-axis oriented MgB2 thin films reveals a pronounced maximum at a temperature around 0.6 times the critical temperature. Calculations in the frame of a two-band model based on Bardeen-Cooper-Schrieffer (BCS) theory suggest that this maximum corresponds to an anomalous coherence peak resembling the two-gap nature of MgB2. Our model assumes there is no interband impurity scattering and a weak interband pairing interaction, as suggested by band structure calculations. In addition, the observation of a coherence peak indicates that the pi band is in the dirty limit and dominates the total conductivity of our films.