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Point-contact spectroscopy of the nickel borocarbide superconductors RNi2B2C (R=Y, Dy, Ho, Er, Tm, Lu)

Yu. G. Naidyuk·D. L. Bashlakov·N. L. Bobrov·V. N. Chernobay·O. E. Kvitnitskaya·I. K. Yanson·G. Behr·S. -L. Drechsler·G. Fuchs·D. Souptel·D. G. Naugle·K. D. D. Rathnayaka·J. H. Ross Jr
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Abstract

An overview of the recent efforts in point-contact (PC) spectroscopy of the nickel borocarbide superconductors RNi2B2C in the normal and superconducting (SC) state is given. The results of measurements of the PC electron- boson(phonon) interaction spectral function are presented. Phonon maxima and crystalline-electric-field (CEF) excitations are observed in the PC spectra of compounds with R=Dy, Ho, Er and Tm, while for R=Y a dominant phonon maximum around 12 meV is characteristic. Additionally, non-phonon and non-CEF maxima are observed near 3 meV in R=Ho and near 6 meV in R=Dy. Directional PC study of the SC gap gives evidence for the multi-band nature of superconductivity in R=Y, Lu. At low temperature the SC gap in R=Ho exhibits a standard single-band BCS-like dependence, which vanishes above T_c^*= 5.6K< T_c=8.5K, where a specifc magnetic ordering starts to play a role. For R=Tm (T_c=10.5 K) a decrease of the SC gap is observed below 5 K.

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Yu. G. Naidyuk, D. L. Bashlakov, N. L. Bobrov, V. N. Chernobay, O. E. Kvitnitskaya, I. K. Yanson, G. Behr, S. -L. Drechsler, G. Fuchs, D. Souptel, D. G. Naugle, K. D. D. Rathnayaka, J. H. Ross Jr. 2006-09-29. Point-contact spectroscopy of the nickel borocarbide superconductors RNi2B2C (R=Y, Dy, Ho, Er, Tm, Lu). https://doi.org/10.1016/j.physc.2007.03.166

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