Terahertz electrodynamics and superconducting energy gap of NbTiN

Taeyoon Hong; Kyujin Choi; Kyung Ik Sim; Taewoo Ha; Byung Cheol Park; Hirotake Yamamori; Jae Hoon Kim

doi:10.1063/1.4856995

Terahertz electrodynamics and superconducting energy gap of NbTiN

Taeyoon Hong, Kyujin Choi, Kyung Ik Sim, Taewoo Ha, Byung Cheol Park, Hirotake Yamamori, Jae Hoon Kim

Department of Physics

Research output: Contribution to journal › Article › peer-review

16 Citations (Scopus)

Abstract

Terahertz electrodynamics of superconducting NbTiN has been studied in the spectral range of 8-70 cm^-1 above and below the critical temperature of T_c = 14.1 K. Our transmission terahertz time-domain spectroscopy technique allows for independent and accurate determination of both the real part σ₁ and the imaginary part σ₂ of the optical conductivity σ as a function of frequency ω and temperature T without a Kramers-Kronig analysis. A clear signature of the superconducting energy gap Δ(T) is observed in the real part σ₁ of the optical conductivity below T_c, with 2Δ(0) = 36.5 cm ^-1 corresponding to 2Δ(0)/k_BT_c = 3.72. No indication of strong-coupling effects was observed in the imaginary part σ₂ toward zero frequency. Our results, including the temperature dependence of the penetration depth λ(T), are in excellent quantitative agreement with weak coupling BCS theory and Mattis-Bardeen formula.

Original language	English
Article number	243905
Journal	Journal of Applied Physics
Volume	114
Issue number	24
DOIs	https://doi.org/10.1063/1.4856995
Publication status	Published - 2013 Dec 28

Bibliographical note

Funding Information:
This work was supported by the Quantum Metamaterial Research Center Program (NRF-2013R1A5A1A95042043), and the Basic Science Research Program (NRF-2012R1A1A2008979) through the National Research Foundation (NRF) funded by the Ministry of Science, ICT and Future Planning of Korea. We also acknowledge support from the BK Plus Project.

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Physics and Astronomy(all)

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title = "Terahertz electrodynamics and superconducting energy gap of NbTiN",

abstract = "Terahertz electrodynamics of superconducting NbTiN has been studied in the spectral range of 8-70 cm-1 above and below the critical temperature of Tc = 14.1 K. Our transmission terahertz time-domain spectroscopy technique allows for independent and accurate determination of both the real part σ1 and the imaginary part σ2 of the optical conductivity σ as a function of frequency ω and temperature T without a Kramers-Kronig analysis. A clear signature of the superconducting energy gap Δ(T) is observed in the real part σ1 of the optical conductivity below Tc, with 2Δ(0) = 36.5 cm -1 corresponding to 2Δ(0)/kBTc = 3.72. No indication of strong-coupling effects was observed in the imaginary part σ2 toward zero frequency. Our results, including the temperature dependence of the penetration depth λ(T), are in excellent quantitative agreement with weak coupling BCS theory and Mattis-Bardeen formula.",

author = "Taeyoon Hong and Kyujin Choi and Sim, {Kyung Ik} and Taewoo Ha and Park, {Byung Cheol} and Hirotake Yamamori and Kim, {Jae Hoon}",

note = "Funding Information: This work was supported by the Quantum Metamaterial Research Center Program (NRF-2013R1A5A1A95042043), and the Basic Science Research Program (NRF-2012R1A1A2008979) through the National Research Foundation (NRF) funded by the Ministry of Science, ICT and Future Planning of Korea. We also acknowledge support from the BK Plus Project.",

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doi = "10.1063/1.4856995",

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AU - Hong, Taeyoon

AU - Choi, Kyujin

AU - Sim, Kyung Ik

AU - Ha, Taewoo

AU - Park, Byung Cheol

AU - Yamamori, Hirotake

AU - Kim, Jae Hoon

N1 - Funding Information: This work was supported by the Quantum Metamaterial Research Center Program (NRF-2013R1A5A1A95042043), and the Basic Science Research Program (NRF-2012R1A1A2008979) through the National Research Foundation (NRF) funded by the Ministry of Science, ICT and Future Planning of Korea. We also acknowledge support from the BK Plus Project.

PY - 2013/12/28

Y1 - 2013/12/28

N2 - Terahertz electrodynamics of superconducting NbTiN has been studied in the spectral range of 8-70 cm-1 above and below the critical temperature of Tc = 14.1 K. Our transmission terahertz time-domain spectroscopy technique allows for independent and accurate determination of both the real part σ1 and the imaginary part σ2 of the optical conductivity σ as a function of frequency ω and temperature T without a Kramers-Kronig analysis. A clear signature of the superconducting energy gap Δ(T) is observed in the real part σ1 of the optical conductivity below Tc, with 2Δ(0) = 36.5 cm -1 corresponding to 2Δ(0)/kBTc = 3.72. No indication of strong-coupling effects was observed in the imaginary part σ2 toward zero frequency. Our results, including the temperature dependence of the penetration depth λ(T), are in excellent quantitative agreement with weak coupling BCS theory and Mattis-Bardeen formula.

AB - Terahertz electrodynamics of superconducting NbTiN has been studied in the spectral range of 8-70 cm-1 above and below the critical temperature of Tc = 14.1 K. Our transmission terahertz time-domain spectroscopy technique allows for independent and accurate determination of both the real part σ1 and the imaginary part σ2 of the optical conductivity σ as a function of frequency ω and temperature T without a Kramers-Kronig analysis. A clear signature of the superconducting energy gap Δ(T) is observed in the real part σ1 of the optical conductivity below Tc, with 2Δ(0) = 36.5 cm -1 corresponding to 2Δ(0)/kBTc = 3.72. No indication of strong-coupling effects was observed in the imaginary part σ2 toward zero frequency. Our results, including the temperature dependence of the penetration depth λ(T), are in excellent quantitative agreement with weak coupling BCS theory and Mattis-Bardeen formula.

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Terahertz electrodynamics and superconducting energy gap of NbTiN

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