Half-integer Shapiro steps at the 0-pi crossover of a ferromagnetic Josephson junction. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Physical Review Letters Année : 2004

Half-integer Shapiro steps at the 0-pi crossover of a ferromagnetic Josephson junction.

Résumé

We investigate the current-phase relation of S/F/S junctions near the crossover between the 0 and the pi ground states. We use Nb/CuNi/Nb junctions where this crossover is driven both by thickness and temperature. For a certain thickness a non-zero minimum of critical current is observed at the crossover temperature. We analyze this residual supercurrent by applying a high frequency excitation and observe the formation of half-integer Shapiro steps. We attribute these fractional steps to a doubling of the Josephson frequency due to a sin(2*phi) current-phase relation. This phase dependence is explained by the splitting of the energy levels in the ferromagnetic exchange field.
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Dates et versions

hal-00001648 , version 1 (30-05-2004)
hal-00001648 , version 2 (05-07-2004)

Identifiants

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Hermann Sellier, Claire Baraduc, Francois Lefloch, Roberto Calemczuk. Half-integer Shapiro steps at the 0-pi crossover of a ferromagnetic Josephson junction.. Physical Review Letters, 2004, 92, pp.257005. ⟨10.1103/PhysRevLett.92.257005⟩. ⟨hal-00001648v2⟩
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