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TT: Fachverband Tiefe Temperaturen
TT 21: Focus Session: Strongly Disordered Superconductors
TT 21.7: Vortrag
Dienstag, 19. März 2024, 12:30–12:45, H 0104
Finite-size scaling in the vicinity of the BKT transition — •Lea Pfaffinger1, Alexander Weitzel1, Sven Linzen2, Evgenii Il’ichev2, Nicola Paradiso1, and Christoph Strunk1 — 1Experimental and Applied Physics, University Regensburg, Germany — 2Leibniz Institute of Photonic Technology, Jena, Germany
In 2D superconducting thin films the unbinding of thermal vortex-antivortex pairs should lead to a finite resistance above the Berezinskii-Kosterlitz-Thouless (BKT) temperature [1]. However, experimental results often showed a broadened transition by correlated disorder in the samples. Very recently, this was avoided in homogeneously disordered 3nm NbN films grown by atomic layer deposition [2]. Finite size effects were expected to affect the transition for sizes smaller than Λp = 2λ2/d, but surprisingly, the transition in our films agrees with theory down to a width of 10µm ≃ Λp ≪ 2mm. When further reducing the width to w 1µm, we observe a finite resistance even for T<TBKT. We study the evolution of this broadened transition regime vs. width and additionally compare the power law exponent in IV characteristics with theoretical predictions.
[1] J. Kosterlitz, D. Thouless, J. Phys. C: Solid State Phys., 6 (1973) 1181
[2] A. Weitzel et al., Phys. Rev. Lett. 131 (2023) 186002
[3] A. Anderson, J. Lidmar, Phys. Rev. B, 87 (2013) 224506
Keywords: NbN; superconducting thin film; Berezinskii-Kosterlitz-Thouless transition