Infrared and optical properties of pure and cobalt-doped LuNi₂B₂C

الأصل · EN

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 +/- 0.4 kBTc 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 lambdatr=0.33 using an alpha²F(omega) spectrum fit to the resistivity.