Wednesday, 8 November 2017

Terahertz electrodynamics and superconducting energy gap of NbN

Sim, Kyung Ik, Young Chan Jo, Taewoo Ha, Jong Hyeon Kim, Jae Hoon Kim, and Hirotake Yamamori. "Terahertz electrodynamics and superconducting energy gap of NbN." Journal of the Korean Physical Society 71, no. 9 (2017): 571-574.

We have measured the transmission spectra of the conventional Bardeen-Cooper-Schrieffer (BCS) superconductor niobium nitride (NbN) thin films (Tc = 11 K) using terahertz time-domain spectroscopy (THz-TDS) over the spectral range of 10 - 110 cm −1 and the temperature range of 3.9 - 295 K. We extracted both the real part, σ1, and the imaginary part, σ2, of the optical conductivity, σ̃ = σ1 + iσ2, independently and simultaneously, without a Kramers-Kronig analysis. The superconducting gap Δ(T) was observed in the real part of the conductivity, σ1, below Tc = 11 K with a maximum value of 2Δ(0) = 30 cm −1 and the gap ratio 2Δ(0)/kBTc = 3.92.

... Terahertz transmission spectroscopy was performed with TeraView TPS-3000 Pulse Spectrometer over the frequency range of 2 - 120 cm −1 . The reliable spectral ...

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