1. Superconducting phase transitions in disordered NbTiN films
- Author
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Valerii M. Vinokur, S. S. Ustavshikov, M. V. Burdastyh, Thomas Proslier, S. V. Postolova, A. Yu. Mironov, and A. V. Antonov
- Subjects
Phase transition ,Materials science ,FOS: Physical sciences ,lcsh:Medicine ,02 engineering and technology ,01 natural sciences ,Article ,Superconducting properties and materials ,Superconductivity (cond-mat.supr-con) ,Metal ,Condensed Matter::Materials Science ,Atomic layer deposition ,Surfaces, interfaces and thin films ,Condensed Matter::Superconductivity ,0103 physical sciences ,Thin film ,lcsh:Science ,010306 general physics ,Saturation (magnetic) ,Sheet resistance ,Condensed Matter::Quantum Gases ,Superconductivity ,Multidisciplinary ,Condensed matter physics ,Condensed Matter - Superconductivity ,Drop (liquid) ,lcsh:R ,021001 nanoscience & nanotechnology ,visual_art ,visual_art.visual_art_medium ,lcsh:Q ,0210 nano-technology - Abstract
The suppression of superconductivity in disordered systems is a fundamental problem of condensed matter physics. Here we investigate the superconducting niobium-titanium-nitride (Nb_{1-x}Ti_{x}N) thin films grown by atomic layer deposition (ALD) where disorder is controlled by the slight tuning of the ALD process parameters. We observe the smooth crossover from the disorder-driven superconductor-normal metal transition (often reffered to as fermionic mechanism) to the case where bosonic mechanism dominates and increasing disorder leads to formation of metal with Cooper pairing. We show that, in moderately disordered films, the transition to zero-resistance state occurs in a full agreement with the conventional theories of superconducting fluctuations and Berezinskii-Kosterlitz-Thouless transition. However, the critically disordered films violate this accord showing low-temperature features possibly indicating the Bose metal phase. We show that it is the interrelation between film's sheet resistance in the maximum, R_{max}, of the resistive curve R(T) and R_q = h/4e^2 that distinguishes between these two behaviors. We reveal the characteristic features in magnetoresistance of the critically disordered films with R_{max} > R_q, 8 pages, 3 figures
- Published
- 2020