1. Evidence for enhanced phase fluctuations in nanostructured niobium thin films
- Author
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Hsiang-Hsi Kung, Ting-Hui Chen, Wei-Li Lee, Chia-Tso Hsieh, and C. W. Wang
- Subjects
Superconductivity ,Nanostructure ,Materials science ,Condensed matter physics ,Niobium ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry ,Phase (matter) ,0103 physical sciences ,Monolayer ,Hexagonal lattice ,Thin film ,010306 general physics ,0210 nano-technology ,Critical field - Abstract
In a superconducting nanostructure, phase fluctuations are prominent and give rise to finite resistance below superconducting transition temperature ${T}_{c}$. By using a monolayer polymer/nanosphere hybrid we developed previously, we fabricated a large array of interconnected niobium (Nb) honeycomb lattices with the thinnest interconnected linewidth $d$ ranging from 36 nm to 89 nm. The honeycomb cells form a highly ordered triangular lattice with more than ${10}^{8}$ unit cells extending over few ${\mathrm{mm}}^{2}$ area, which enables the detailed transport study at nanometer scales. We found ${T}_{c}$ gradually drops with decreasing $d$ due to the phase-slip effect, while the critical field at lower temperature tends to follow that of a continuous Nb thin film. One likely scenario is to consider a model system of numerous superconducting islands interconnected by short phase-slip junctions, where the phase coherence is dictated by the phase slippage in the nanoconstriction. This was strongly supported by the excellent fitting to the thermally activated phase-slip model and also the unusual phenomena of transition width narrowing in high fields.
- Published
- 2017