Infrared and optical properties of pure and cobalt-doped LuNi_2B_2C

Abstract

We present optical conductivity data for Lu(Ni${}_{1-x}$Co${}_x$)${}_2$B${}_2$C over a wide range of frequencies and temperatures for x=0 and x=0.09. Both materials show evidence of being good Drude metals with the infrared data in reasonable agreement with dc resistivity measurements at low frequencies. An absorption threshold is seen at approximately 700 cm-1. In the cobalt-doped material we see a superconducting gap in the conductivity spectrum with an absorption onset at 24 +/- 2 cm-1 = 3.9$ +/- 0.4 k_BT_c suggestive of weak to moderately strong coupling. The pure material is in the clean limit and no gap can be seen. We discuss the data in terms of the electron-phonon interaction and find that it can be fit below 600 cm-1 with a plasma frequency of 3.3 eV and an electron-phonon coupling constant lambda_{tr}=0.33 using an alpha^{2}F(omega) spectrum fit to the resistivity.

arXiv comment10 pages with 10 embedded figures, submitted to PRB

References in corpus (4)

• Upper critical field pecularities of superconducting YNi2B2C and LuNi2B2C
• Low Energy Quasiparticle Excitation in the Vortex State of Borocarbide Superconductor YNi_2B_2C
• A study of the superconducting gap in RNi${}_2$B${}_2$C (R = Y, Lu) single crystals by inelastic light scattering
• Electron-Phonon Coupling Origin of the resistivity in YNi_{2}B_{2}C Single Crystals