Spintransport und Spinfilterung in Supraleiter-Nanostrukturen

• Antragsteller: Professor Dr. Detlef Beckmann
• Fachliche Zuordnung: Experimentelle Physik der kondensierten Materie
• Förderung: Förderung von 2014 bis 2019
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 257644405

• Erstellungsjahr: 2018

Zusammenfassung der Projektergebnisse

Superconducting spintronics aims at using the spin degree of freedom to implement electronic functionality in superconducting-ferromagnet hybrid structures. This may involve both triplet Cooper pairs or spin-polarized quasiparticles. In this project, we have focused on nonequilibrium quasiparticles in high-field superconductors, which are characterized by a spin splitting of the density of states. We have performed the first proof-of-principle experiment to demonstrate spin-dependent thermoelectric effects in superconductor-ferromagnet tunnel junctions. These thermoelectric effects are the consequence of coupled spin and heat transport in high-field superconductors, and yield very large Seebeck coefficients, on the order of 100 µV/K. We have also shown that the thermoelectric effects can be further enhanced by the proximity effect with a magnetic insulator. In addition, we have investigated non-local thermoelectric effects, which are caused by thermal injection of quasiparticles into high-field superconductors and help to elucidate the mechanism of spin transport. Possible applications of these effects are highly sensitive local electron thermometers, particle detectors and efficient Peltier microrefrigerators.

Projektbezogene Publikationen (Auswahl)

• Nonlinear thermoelectric effects in highfield superconductor-ferromagnet tunnel junctions, Beilstein J. Nanotechnol. 7, 1579 (2016)
  S. Kolenda, P. Machon, D. Beckmann, and W. Belzig
  
• Observation of Thermoelectric Currents in High-Field Superconductor-Ferromagnet Tunnel Junctions, Phys. Rev. Lett. 116, 097001 (2016)
  S. Kolenda, M. J. Wolf, and D. Beckmann
  
• Spin manipulation in nanoscale superconductors, J. Phys.: Condens. Matter 28, 163001 (2016)
  D. Beckmann
  
• Thermoelectric effects in superconductorferromagnet tunnel junctions on europium sulfide, Phys. Rev. B 95, 224505 (2017)
  S. Kolenda, C. Sürgers, G. Fischer, and D. Beckmann
  
• Yu-Shiba-Rusinov bands in superconductors in contact with a magnetic insulator, J. Magn. Magn. Mater. 459, 276 (2018)
  W. Belzig and D. Beckmann