Quasiparticle conductance in Spin Valve Josephson Structures

Abstract

We study the quasiparticle current in clean ferromagnetic Josephson structures of the form $S_1/F_1/N/F_2/S_2$, where $S$, $F$, and $N$ denote superconducting, ferromagnetic or normal layers respectively. Our focus is on the structure of the conductance $G$ as a function of bias $V$, emphasizing the subgap region. We use a fully self consistent numerical method, coupled to a transfer matrix procedure to extract $G(V)$. We choose material parameters appropriate to experimentally realized Co Cu Nb structures. We find a resonance peak structure as a function of the intermediate layer thickness and of the misalignement angle $\varphi$ between $F$ layers. To understand this resonance structure, we develop an approximate analytic method. For experimentally relevant thicknesses, the conductance has multiple subgap peaks which oscillate in position between low and critical bias positions. These oscillations occur in both $\varphi$ and the layer thicknesses. We compare our results with those obtained for the spin valve structures $(F_1/N/F_2/S_2)$ and discuss the implications of our results for the fabrication of spin Josephson devices.

16 pages including figures

References in corpus (31)

• Odd Triplet Superconductivity and Related Phenomena in Superconductor-Ferromagnet Structures
• Coupling of two superconductors through a ferromagnet : evidence for a pi-junction
• A spin triplet supercurrent through the half-metallic ferromagnet CrO2
• Spin-polarized supercurrents for spintronics: a review of current progress
• Triplet supercurrents in clean and disordered half-metallic ferromagnets
• Controllable 0-pi Josephson junctions containing a ferromagnetic spin valve
• Evidence for Triplet Superconductivity in a Superconductor-Ferromagnet Spin Valve
• Superconducting pi qubit with a ferromagnetic Josephson junction
• Ferromagnetic Josephson switching device with high characteristic voltage
• Magnetic Josephson Junctions with Superconducting Interlayer for Cryogenic Memory
• Optimization of spin-triplet supercurrent in ferromagnetic Josephson junctions
• Proximity Effect and Multiple Andreev Reflections in Diffusive SNS Junctions
• Anomalous current in diffusive ferromagnetic Josephson junctions
• Crossover from the Josephson effect to bulk superconducting flow
• Half-Metallic Superconducting Triplet Spin Valve
• Angular dependence of superconductivity in superconductor / spin valve heterostructures
• Proximity effects and characteristic lengths in ferromagnet-superconductor structures
• Inverse proximity effect at superconductor-ferromagnet interfaces: Evidence for induced triplet pairing in the superconductor
• Josephson current carried by Andreev levels in superconducting quantum point contacts
• Spin-valve Josephson junctions for cryogenic memory
• Layered ferromagnet-superconductor structures: the $\pi$ state and proximity effects
• Supercurrent in ferromagnetic Josephson junctions with heavy metal interlayers
• Charge and Spin Currents in Ferromagnetic Josephson junctions
• Tunneling Conductance and Spin Transport in Clean Ferromagnet-Ferromagnet-Superconductor Heterostructures
• Self-consistent scattering description of transport in normal-superconductor structures
• Subharmonic gap structures and Josephson effect in MgB2/Nb micro-constrictions
• Transport in Ferromagnet/Superconductor spin valves
• Spin current and spin transfer torque in ferromagnet/superconductor spin valves
• Subgap anomaly and above-energy-gap structure in chains of diffusive SNS junctions
• Spin-polarized multiple Andreev reflections in spin-split superconductors
• Spin-split conductance and subgap peak in ferromagnet/superconductor spin valve heterostructures

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• Cubic spin-orbit coupling and anomalous Josephson effect in planar junctions
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• Superconducting spin valves based on antiferromagnet/superconductor/antiferromagnet heterostructures
• Inverse proximity effect in thin-film superconductor/magnet heterostructures with metallic and insulating magnets
• Triplet correlations in superconductor/antiferromagnet heterostructures: dependence on type of antiferromagnetic ordering