Sensitivity of the superconducting state in thin films

I. Tamir (1) , A. Benyamini (2) , E. Telford (2) , F. Gorniaczyk (1) , A. Doron (1) , T. Levinson (1) , D. Wang (2) , F. Gay (3) , Benjamin Sacépé (4) , J. Hone (2) , K. Watanabe (5) , T. Taniguchi (5) , C. Dean (6) , A. Pasupathy (2) , D. Shahar (1)

1 Weizmann Institute of Science [Rehovot, Israël]
2 Columbia University [New York]
3 NEEL - AUTOCARAC - Automatisation & caractérisation
4 NEEL - QuNES - Nano-Electronique Quantique et Spectroscopie
5 NIMS - National Institute for Materials Science
6 McGill University = Université McGill [Montréal, Canada]

For more than two decades, there have been reports on an unexpected metallic state separating the established superconducting and insulating phases of thin-film superconductors. To date, no theoretical explanation has been able to fully capture the existence of such a state for the large variety of superconductors exhibiting it. Here, we show that for two very different thin-film superconductors, amorphous indium oxide and a single crystal of 2H-NbSe 2 , this metallic state can be eliminated by adequately filtering external radiation. Our results show that the appearance of temperature-independent, metallic-like transport at low temperatures is sufficiently described by the extreme sensitivity of these superconducting films to external perturbations. We relate this sensitivity to the theoretical observation that, in two dimensions, superconductivity is only marginally stable.

Domaines: Supraconductivité [cond-mat.supr-con]; Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

I. Tamir, A. Benyamini, E. Telford, F. Gorniaczyk, A. Doron, et al.. Sensitivity of the superconducting state in thin films. Science Advances , 2019, 5 (3), pp.aau3826. ⟨10.1126/sciadv.aau3826⟩. ⟨hal-02072775⟩