Superconducting gap anisotropy in LuNi$_{2}$B$_{2}$C by point-contact spectroscopy

The superconducting gap anisotropy in non-magnetic members of the intermetallic borocarbide family still remains controversial. Several scenarios have been proposed including the s+g pairing symmetry and multi-band/multi-gap superconductivity. In order to address this issue, especially the puzzling existence of point nodes along $a$- and $b$-axis, we apply the point-contact spectroscopy technique to investigate the superconducting gap structure of single crystals LuNi$_{2}$B$_{2}$C ($T_{c}\sim $16.5 K) along three different crystallographic orientations. \textit{ab}-plane surfaces are prepared by embedding and polishing crystals and their orientations are confirmed by X-ray diffraction. Our preliminary conductance data, analyzed by the one-band Blonder-Tinkham-Klapwijk model, show anisotropic gap values, $\sim $1.6 meV and $\sim $2.6 meV, along (001) and (110) directions, respectively. We will discuss the possible origin for the gap anisotropy.