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Ferromagnetic 0-pi Junctions as Classical Spins

M. L. Della Rocca·M. Aprili·T. Kontos·A. Gomez·P. Spatkis
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Abstract

The ground state of highly damped PdNi based 0-pi ferromagnetic Josephson junctions shows a spontaneous half quantum vortex, sustained by a supercurrent of undetermined sign. This supercurrent flows in the electrode of a Josephson junction used as a detector and produces a phi(0)/4 shift in its magnetic diffraction pattern. We have measured the statistics of the positive or negative sign shift occurring at the superconducting transition of such a junction. The randomness of the shift sign, the reproducibility of its magnitude and the possibility of achieving exact flux compensation upon field cooling: all these features show that 0-pi junctions behave as classical spins, just as magnetic nanoparticles with uniaxial anisotropy.

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M. L. Della Rocca, M. Aprili, T. Kontos, A. Gomez, P. Spatkis. 2005-01-19. Ferromagnetic 0-pi Junctions as Classical Spins. https://doi.org/10.1103/physrevlett.94.197003

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