| Half-Integer Shapiro Steps at the 0-? Crossover of a Ferromagnetic Josephson Junction (2004) | |||||||||||
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| VOLUME NUMBER PHYSICA EVIEW LET ERS week ending JUNE Half Integer Shapiro Steps the Crossover Ferromagnetic Josephson Junction Hermann Sellier Claire Baraduc Francois Lefloch and Roberto Calemczuk Departement Recherche Fondamentale sur Matiere Condensee CEA Grenoble rue des Martyrs Grenoble France Kavli Institute Nanoscience Delft University Technology Lorentzweg Delft The Netherlands Received February published June investigate the current phase relation S junctions near the crossover between the and the ground states use CuNi junctions where this crossover driven both thickness and temperature For certain thickness nonzero minimum critical current observed the crossover temperature analyze this residual supercurrent applying high frequency excitation and observe the formation half integer Shapiro steps attribute these fractional steps doubling the Josephson frequency due sin current phase relation This phase dependence explained the splitting the energy levels the ferromagnetic exchange field DOI PhysRevLett PACS numbers c The current phase relation ballistic and diffusive junctions predicted strongly nonsinusoidal zero temperature contrast that tunnel junctions This due different conductivity mechanism involving Andreev bound states created the normal metal the superconductors These states are sensitive the superconducting phase difference and carry the supercurrent S junctions the current phase relation strongly distorted the exchange field the ferromagnet and can even re | |||||||||||
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