Long range Josephson coupling through ferromagnetic graphene

Abstract

We study the Josephson effect in graphene-based ballistic superconductor-ferromagnet-superconductor (SFS) junctions. We find an oscillatory Josephson coupling $I_c{R}_N$ of F graphene whose amplitude is nonvanishing for a half-metallic graphene, increases for the exchange fields $h$ above the Fermi energy $E_F$ and shows only a slow damping at strong exchange fields $h\gg E_F$. We interpret this long range Josephson coupling as the result of the exchange mediated Andreev-Klein process at FS interfaces which enhances the induced antiparallel-spin superconducting correlations in F graphene by increasing $h$ above $E_F$. We further demonstrate the existence of regular temperature induced transitions between 0 and $\pi$ couplings in the plane of $T$ and $h$ where the phase boundaries have distinct shapes at the two regimes of $h$ below and above $E_F$.

4 pages, 2 figures

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• Proximity coupling in superconductor-graphene heterostructures
• Spin-dependent Seebeck effect and spin caloritronics in magnetic graphene
• Josephson current in graphene: the role of unconventional pairing symmetries
• Andreev-Klein reflection in graphene ferromagnet-superconductor junctions
• Spin-controlled superconductivity and tunable triplet correlations in graphene nanostructures
• Critical Josephson current in ballistic superconductor-graphene systems
• Planar graphene-NbSe${}_2$ Josephson junctions in a parallel magnetic field
• Enhanced Andreev reflection in gapped graphene
• Triplet proximity effect and odd-frequency pairing in graphene
• Coherent transport of armchair graphene constrictions
• Gate-controlled supercurrent reversal in MoS${}_2$-based Josephson junctions
• Relativistic model for electron-hole pairing in the superconducting state of graphene-based materials
• Gate controllable spin pumping in graphene via rotating magnetization
• Boltzmann conductivity of ferromagnetic graphene with magnetic impurities
• Supercurrent reversal in Josephson junctions based on bilayer graphene flakes
• Anomalous quantum interference effects in graphene SNS junctions due to strain-induced gauge fields
• Quantum transport of pseudospin-polarized Dirac fermions in gapped graphene nanostructures
• Magnetically modulated superconductor-graphene-superconductor (SGS) Josephson junctions and their tunability