2004/06/10 by H. Sellier, C. Baraduc, F. Lefloch +1 · 4 citations
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.92.257005
published as Phys. Rev. Lett. 92, 257005 (2004) · 4 pages, 5 figures, accepted for publication in Phys. Rev. Lett
arxiv created 2004/06/10 · openalex publication_date 2004/06/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
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 nonzero 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((2phi) current-phase relation. This phase dependence is explained by the splitting of the energy levels in the ferromagnetic exchange field.