Disorder effects in NbTiN superconducting resonators

Abstract Disordered superconducting materials like NbTiN possess high kinetic inductance fraction and adjustable critical temperature, making them a good choice for low-temperature detectors. Their energy gap (Δ), critical temperature (Tc), and quasiparticle density of states (QDOS) distribution, ho...

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Bibliographic Details
Published in:Chinese physics B 2024-01, Vol.33 (2)
Main Authors: Lyu, Wei-Tao, Zhi, Qiang, Hu, Jie, Li, Jing, Shi, Sheng-Cai
Format: Article
Language:English
Subjects:
complex conductivity
effects of disorder
NbTiN
superconducting film
superconducting resonator
Usadel equation
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Summary:Abstract Disordered superconducting materials like NbTiN possess high kinetic inductance fraction and adjustable critical temperature, making them a good choice for low-temperature detectors. Their energy gap (Δ), critical temperature (Tc), and quasiparticle density of states (QDOS) distribution, however, are deviated from the classical BCS theory due to the disorder effects. The Usadel equation, which takes account of elastic scattering, non-elastic scattering, and electro-phonon coupling, can be applied to explain and describe these deviations. This paper presents numerical simulations of the disorder effects based on the Usadel equation to investigate their effects on Δ, Tc, QDOS distribution, and complex conductivity of the NbTiN film. Furthermore, NbTiN superconducting resonators with coplanar waveguide (CPW) structures are fabricated and characterized at different temperatures to validate our numerical simulations. The pair-breaking parameter α and the critical temperature in the pure state Tc P of our NbTiN film are determined through experimental results and numerical simulations. This study has significant implications for the development of low-temperature detectors made of disordered superconducting materials.
ISSN:1674-1056
2058-3834
DOI:10.1088/1674-1056/ad03dc