Superconducting order parameter in nonmagnetic borocarbides RNi$ {2}$B$ {2}$C R=Y, Lu probed by point-contact Andreev reflection spectroscopy - Condensed Matter > SuperconductivityReport as inadecuate




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Abstract: We report on the measurements of the superconducting order parameter in thenonmagnetic borocarbides LuNi$ 2$B$ 2$C and YNi$ 2$B$ 2$C. Andreev conductancespectra are obtained from nanoscale metallic junctions on single crystalsurfaces prepared along three major crystallographic orientations: 001,110, and 100. The gap values extracted by the single-gapBlonder-Tinkham-Klapwijk model follow the BCS predictions as a function oftemperature and magnetic field and exhibit a small anisotropy. Theseobservations are robust and reproducible among all the measurements on twodifferent sets of LuNi$ 2$B$ 2$C crystals and one set of YNi$ 2$B$ 2$Ccrystals. We suggest possible explanations for the small gap anisotropy basedon the recent detailed gap measurements by angle-resolved photoemissionspectroscopy and the tunneling cone effect. Our results provide a consistentpicture of the superconducting gap structure in these materials, addressing thecontroversy particularly in the reported results of point-contact Andreevreflection spectroscopy.



Author: X. Lu, W. K. Park, S. Yeo, K.-H. Oh, S.-I. Lee, S. L. Bud'ko, P. C. Canfield, L. H. Greene

Source: https://arxiv.org/







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