Direct observation of the superconducting energy-gap opening in the optical conductivity spectra of LuNi2B2C


Direct observation of the superconducting energy-gap opening in the optical conductivity spectra of LuNi2B2C

Fischer, T.; Pronin, A. V.; Stehr, D.; Wosnitza, J.; Niemeier, T.; Holzapfel, B.

At frequencies between 100 GHz and 2.5 THz, we have accurately measured the complex transmission coefficient of LuNi2B2C films on MgO substrates using two different setups: a time-domain terahertz spectrometer and a setup based on backward-wave oscillators. For the first time, the development of the superconducting energy gap is directly observed in the optical spectra. From the measured data, we have calculated the optical conductivity and the penetration depth. We have compared the results with the BCS theory, and found an additional absorption at low frequencies. The origin of this absorption may be related to the complex gap structure of the compound with possible nodes. Theoretical calculations are currently under way. Part of this work has been supported by EuroMagNET, EU contract 228043.

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    Frühjahrstagung der DPG, 26.-30.03.2012, Berlin, Deutschland

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Publ.-Id: 16945