Infrared and optical properties of pure and cobalt-dopedLuNi2B2C

Abstract

We present optical conductivity data for Lu(Ni1−xCox)2B2C 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±0.4kB Tc 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 λtr = 0.33 using an α 2 F (ω) spectrum fit to the resistivity.

Raman- and infrared-active phonons in superconducting and nonsuperconducting rare-earth transition-metal borocarbides from full-potential calculations

“…Usually the infrared ͑IR͒-active phonon frequencies are measured by IR ellipsometry. Windt et al 41 studied the IR and optical properties of LuNi 2 B 2 C and suggested weak to moderately strong coupling in this material. However, the IR-active phonon frequencies for these materials have not yet been determined experimentally and hence a theoretical study is highly relevant.…”

Optical properties ofRNi2B2CRhee1, Harmon2 2002Phys. Rev. B1000View full textAdd to dashboardCite

“…17, particularly͒. Our calculation suggests that there should be not too strong but clearly observable interband transitions at slightly different energies; 0.12 and 0.2 eV for YNi 2 B 2 C and 0.1 and 0.3 eV for LuNi 2 B 2 C ͑see the insets of Figs.…”

“…There are several measurements of optical properties of rare-earth nickel borocarbide compounds. [13][14][15][16][17][18] The first experiments were mainly concerned with the relationship between the far-infrared ͑FIR͒ optical conductivity ͑OC͒ and the superconducting gap. A few of these experimental studies did obtain the interband optical absorption, however, there are quite large variations in the various reported experimental OC spectra.…”