# Berlin 2015 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# TT: Fachverband Tiefe Temperaturen

## TT 66: Superconductivity: Tunneling, Josephson Junctions, SQUIDs

### TT 66.7: Vortrag

### Mittwoch, 18. März 2015, 16:30–16:45, H 2053

**Experiments on phase retrapping in ****ϕ**** Josephson junctions** — •Edward Goldobin^{1}, Rosina Menditto^{1}, Martin Weides^{2}, Dieter Koelle^{1}, and Reinhold Kleiner^{1} — ^{1}University of Tübingen, Tübingen, Germany — ^{2}KIT, Karlsruhe, Germany

We experimentally study retrapping of the phase in ϕ Josephson junctions (JJs) based on superconductor-insulator-ferromagnet-superconductor (SIFS) 0-π heterostructures[1,2]. Such ϕ JJs have a doubly degenerate ground state (two potential energy wells) with the phases ±ϕ (0<ϕ<π). We study in which of these two wells the phase is trapped upon return of the JJ to the zero voltage state. We find that for *T*>*T*^{*}≈2.4 *K* (large damping) the phase is always trapped in the +ϕ state. However, for lower *T* (small damping) the trapping result is a statistical mixture of the +ϕ and the −ϕ states due to the presence of noise in the system. The probability for retrapping to the −ϕ state increases and oscillates as *T* is decreasing below *T*^{*}, reaching a saturation value of ∼ 30% for *T*1.2 *K*. These results are compared with theory[3], which predicts the butterfly effect in the limit of low damping.

[1] E. Goldobin et al. Phys. Rev. Lett. **107**, 227001 (2011).

[2] H. Sickinger et al. Phys. Rev. Lett. **109**, 107002 (2012).

[3] E. Goldobin et al. Phys. Rev. Lett. **111**, 057004 (2013).