Zusammenspiel zwischen Supraleitung und Lokalisierung

• Antragsteller: Privatdozent Dr. Igor Gornyi
• Fachliche Zuordnung: Theoretische Physik der kondensierten Materie
• Förderung: Förderung von 2015 bis 2019
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 277365008

• Erstellungsjahr: 2019

Zusammenfassung der Projektergebnisse

The project was devoted to the theoretical study of phase transitions between superconducting, metallic, and insulating states in disordered interacting systems. The fundamental theoretical problem addressed in the project was that of the interplay of superconductivity, localization, and electronic correlations. The major direction of the project was related to low-dimensional disordered superconducting structures. One of the central questions within this direction is the nature of the Superconductor- Insulator Transition (SIT) in disordered systems, its degree of universality, and character of transport in its vicinity. The project developed a coherent picture of disordered superconductors involving all the key ingredients: superconducting correlation, disorder-induced multifractality, and electron-electron interactions in various channels. The emphasis was put on superconducting properties of thin films demonstrating the SIT and novel superconducting materials. The main research topics of the project were: Overall phase diagram of the SIT; Magnetoresistance near the SIT; Enhancement of the superconducting critical temperature by screening of long-range Coulomb interaction; Tunneling density of states (DoS) and its fluctuations; Superconducting correlations in the localized state; Fluctuations of the order-parameter phase and Berezinskii-Kosterlitz-Thouless transition. In addition to the study of the SIT in two-dimensional films, a conceptually similar study of the SIT in one-dimensional Josephson-junction arrays was performed. In addition, the superconducting proximity effect in bilayer-graphene nanosystems was investigated in a joint experiment-theory paper. Theoretical results of the project are highly relevant for ongoing and future experiments in the field. In particular, the project addressed a complex of problems whose solution appears to be of fundamental importance for exploring the possibilities of obtaining high temperature superconductivity in novel materials.

Projektbezogene Publikationen (Auswahl)

• “Berezinskii-Kosterlitz-Thouless transition in homogeneously disordered superconducting films”, Physical Review B 92, 214503 (2015)
  E.J. König, A. Levchenko, I.V. Protopopov, I.V. Gornyi, I.S. Burmistrov, and A.D. Mirlin
  
• “Superconductor-insulator transitions: Phase diagram and magnetoresistance", Physical Review B 92, 014506 (2015)
  I.S. Burmistrov, I.V. Gornyi, and A.D. Mirlin
  
• “Local density of states and its mesoscopic fluctuations near the transition to a superconducting state in disordered systems”, Physical Review B 93, 205432 (2016)
  I.S. Burmistrov, I.V. Gornyi, and A.D. Mirlin
  
• “Mesoscopic fluctuations of the local density of states in interacting electron systems”, JETP Letters 106, 272 (2017)
  I.S. Burmistrov, I.V. Gornyi, and A. D. Mirlin
  
• “Superconductor-Insulator Transition in disordered Josephson junction chains”, Physical Review B 96, 064514 (2017)
  M. Bard, I.V. Protopopov, I.V. Gornyi, A. Shnirman, and A.D. Mirlin
  
• “Tailoring supercurrent confinement in graphene bilayer weak links”, Nature Communications 9, 1722 (2018)
  R. Kraft, J. Mohrmann, R. Du, P.B. Selvasundaram, M. Irfan, U.N. Kanilmaz, F. Wu, D. Beckmann, H. von Löhneysen, R. Krupke, A. Akhmerov, I. Gornyi, and R. Danneau