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Article Dans Une Revue Physical Review B: Condensed Matter and Materials Physics (1998-2015) Année : 2019

Nonuniform superconductivity and Josephson effect in a conical ferromagnet

Résumé

Using the Gorkov equations, we provide an exact solution for a one-dimensional model of superconductivity in the presence of a conical helicoidal exchange field. Due to the special type of symmetry of the system, the superconducting transition always occurs into a nonuniform superconducting phase (in contrast with the Fulde-Ferrell-Larkin-Ovchinnikov state, which appears only at low temperatures). We directly demonstrate that the uniform superconducting state in our model carries a current and thus does not correspond to the ground state. We study in the framework of the Bogoliubov-de Gennes approach the properties of the Josephson junction with a conical ferromagnet as a weak link. In our numerical calculations, we do not use any approximations (such as, e.g., a quasiclassical approach), and we show a realization of an anomalous φ 0 junction (with a spontaneous phase difference φ 0 in the ground state). The spontaneous phase difference φ 0 strongly increases at high values of the exchange field near the borderline with a half-metal, and it exists also in the half-metal regime.
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Dates et versions

hal-02140469 , version 1 (27-05-2019)

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Hao Meng, A. V Samokhvalov, Alexandre I. Buzdin. Nonuniform superconductivity and Josephson effect in a conical ferromagnet. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2019, 99 (2), ⟨10.1103/PhysRevB.99.024503⟩. ⟨hal-02140469⟩

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