Superconducting gap and electron-phonon interaction in MgB₂ thin film studied by point contacts

2001/10/31 by N. L. Bobrov, P. N. Chubov, Yu. G. Naidyuk +6
Physics and Astronomy · #cond-mat.supr-con

paper · pdf

published as in {\it New Trends in Superconductivity}, ed. by J. F. Annett and S. Kruchinin, (Kluwer Academic Publisher, 2002) NATO Science Series II: Mathematics, Physics and Chemistry, Vol.67, p.225-234. · V2. Refs. [17, 23, 24, 34, 40] are added, plain text improvements, 5 pages incl. 4 figures, RevTex4. Presented at the NATO ARW "New Trends in Superconductivity", Yalta, Ukraine, 16-20 Sept. 2001

arxiv created 2001/11/20 · arxiv updated 2009/11/30

Abstract

The superconducting order parameter and electron-phonon interaction (EPI) in a MgB₂ c-axis oriented thin film are investigated by point contacts (PCs). Two superconducting gaps Δ_Small≈ 2.6 meV and Δ_Large≈ 7.4 meV have been established, which fairly well correspond to the theoretical gap ratio 1:3. The reconstructed PC EPI function along c-axis has above 30 meV similarities with the phonon DOS, while a pronounced maximum around 20 meV is resolved pointing out that the low frequency phonon mode can be of importance for pairing. We have estimated the Fermi velocity in MgB₂ about 5× 10⁷ cm/s.

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