Onset of a superconductor-insulator transition in an ultrathin NbN film under in-plane magnetic field studied by terahertz spectroscopy

Article

关键词: BEHAVIOR;    ALLOYS;   

DOI  :  10.1103/PhysRevB.105.014506

来源: SCIE

【 摘 要 】

Optical conductivity of a moderately disordered superconducting NbN film was investigated by terahertz time-domain spectroscopy in an external magnetic field applied along the film plane. The film thickness of similar to 5 nm was comparable with the coherence length, so vortices should not form. This was confirmed by the fact that no marked difference between the spectra with a terahertz electric field set perpendicular and parallel to the external magnetic field was observed. Simultaneous use of Maxwell-Garnett effective medium theory and the model of optical conductivity by Herman and Hlubina [Phys. Rev. B 96, 014509 (2017)] proved to correctly reproduce the terahertz spectra obtained experimentally in a magnetic field of up to 7 T. This let us conclude that the magnetic field tends to suppress the superconductivity, resulting in an inhomogeneous state where superconducting domains are enclosed within a normal-state matrix. The scattering rate due to pair-breaking effects was found to linearly increase with the magnetic field.

【 授权许可】

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