Strong-Coupling Features in YB6 and ZrB12 Studied by Point-Contact Spectroscopy

J. Girovskýa, P. Szabóa, T. Morib and P. Samuelya aCentre of Low Temperature Physics, IEP Slovak Academy of Sciences & P.J. Šafárik University, Watsonova 47, SK-04353 Košice, Slovakia bAdvanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan

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Point-contact spectroscopy studies of the superconducting energy gap and the electron-phonon coupling mechanism are performed on the boron rich YB6 and ZrB12 single crystals. The obtained values of the superconducting energy gaps suggest the strong coupling with 2 Δp/kB Tc ≈ 4.2 for YB6 and 2 Δp/kB Tc ≈ 4.15 for ZrB12. We have observed the dominant soft phonon modes mediating superconductivity in the both samples at energy ≈ 8 meV for YB6 and ≈ 11 meV in ZrB12, respectively.

DOI: 10.12693/APhysPolA.118.1042 PACS numbers: 74.50.+r, 74.70.Ad, 74.62.Dh