Bauer, A and Bentner, J and Aprili, M and Della Rocca, L and Reinwald, Matthias and Wegscheider, Werner and Strunk, Christoph
Spontaneous Supercurrent Induced by Ferromagnetic π Junctions.
Physical Review Letters (PRL) 92 (21), p. 217001.
Other URL: http://link.aps.org/doi/10.1103/PhysRevLett.92.217001
We present magnetization measurements of mesoscopic superconducting niobium loops containing a ferromagnetic (PdNi) π junction. The loops are prepared on top of the active area of a micro-Hall sensor based on high mobility GaAs/AlGaAs heterostructures. We observe asymmetric switching of the loop between different magnetization states when reversing the sweep direction of the magnetic field. This provides evidence for a spontaneous current induced by the intrinsic phase shift of the π junction. In addition, the presence of the spontaneous current near zero applied field is directly revealed by an increase of the magnetic moment with decreasing temperature, which results in half integer flux quantization in the loop at low temperatures.