Experimental observation of electron-phonon coupling enhancement in Sn nanowires caused by phonon confinement effects

Lozano, D. P.;Couet, S.;Petermann, C.;Hamoir, G.;Van Bael, M. J.;et.al.
(2019) Physical Review B — Vol. 99, n° 6, p. 064512-064511 (2019)

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Authors
  • Lozano, D. P.KU Leuven, Instituut voor Kern-en Stralingsfysica, Leuven,Belgium
    Author
  • Couet, S.KU Leuven, Instituut voor Kern-en Stralingsfysica, Leuven,Belgium
    Author
  • Petermann, C.KU Leuven, Instituut voor Kern-en Stralingsfysica, Leuven, Belgium
    Author
  • Hamoir, G.UCLouvain
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  • Piraux, LucUCLouvain
    Author
  • Van Bael, M. J.KU Leuven, Laboratory of Solid-State Physics and Magnetism, Leuven, Belgium
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Abstract
Reducing the size of a superconductor below its characteristic length scales can either enhance or suppress its critical temperature (Tc). Depending on the bulk value of the electron-phonon coupling strength, electronic and phonon confinement effects will play different roles in the modification of Tc. Experimentally disentangling each contribution has remained a challenge. We have measured both the phonon density of states and Tc of Sn nanowires with diameters of 18, 35, and 100 nm in order to quantify the effects of phonon confinement on superconductivity. We observe a shift of the phonon frequency towards the low-energy region and an increase in the electron-phonon coupling constant that can account for the measured increase in Tc.
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Citations

Lozano, D. P., Couet, S., Petermann, C., Hamoir, G., Jochum, J. K., Picot, T., Menéndez, E., Houben, K., Joly, V., Antohe, V. A., Hu, M. Y., Leu, B. M., Alatas, A., Said, A. H., Roelants, S., Partoens, B., Milošević, M. V., Peeters, F. M., Piraux, L., et al. (2019). Experimental observation of electron-phonon coupling enhancement in Sn nanowires caused by phonon confinement effects. Physical Review B, 99(6), 064512-064511. https://doi.org/10.1103/physrevb.99.064512 (Original work published 2019)