Andreev-Klein reflection in graphene ferromagnet-superconductor junctions

Abstract

We show that Andreev reflection in a junction between ferromagnetic (F) and superconducting (S) graphene regions is fundamentally different from the common FS junctions. For a weakly doped F graphene with an exchange field $h$ larger than its Fermi energy $E_{\mathrm{F}}$, Andreev reflection of massless Dirac fermions is associated with a Klein tunneling through an exchange field p-n barrier between two spin-split conduction and valence subbands. We find that this Andreev-Klein process results in an enhancement of the subgap conductance of a graphene FS junction by $h$ up to the point at which the conductance at low voltages $eV\ll \Delta$ is greater than its value for the corresponding non-ferromagnetic junction. We also demonstrate that the Andreev reflection can be of retro or specular types in both convergent and divergent ways with the reflection direction aligned, respectively, closer to and farther from the normal to the junction as compared to the incidence direction.

4 pages, 2 figures

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Cited by in corpus (21)

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• Spin-dependent Seebeck effect and spin caloritronics in magnetic graphene
• Graphene-based electronic spin lenses
• Josephson current in graphene: the role of unconventional pairing symmetries
• Tunable Anomalous Andreev Reflection and Triplet Pairings in Spin Orbit Coupled Graphene
• Tunneling conductance of graphene ferromagnet-insulator-superconductor junctions
• Thermal Transport Properties of Graphene-Based F/S/F Junctions
• Anisotropic RKKY interaction in spin polarized graphene
• Enhanced Andreev reflection in gapped graphene
• Signatures of d-Wave Symmetry on Thermal Dirac Fermions in Graphene-Based F/I/d Junctions
• Spin-dependent thermoelectric effects in graphene based superconductor junctions
• Andreev reflection of massive pseudospin-1 fermions
• Relativistic model for electron-hole pairing in the superconducting state of graphene-based materials
• Charge and spin Hall effect in spin chiral ferromagnetic graphene
• Andreev reflection and subgap conductance in monolayer $Mo{S}_2$ ferromagnet/$s$ and $d$-wave superconductor junction
• Boltzmann conductivity of ferromagnetic graphene with magnetic impurities
• Electrical and thermal transport through $\alpha -T_3$ NIS junction
• Thermopower generation and thermoelectric cooling in a Kane-Mele normal-insulator-superconductor nano-junction
• Effect of helical edge states on the tunneling conductance in ferromagnet/noncentrosymmetric superconductors junctions
• Asymmetric Andreev resonant state with a magnetic exchange field in spin-triplet superconducting monolayer $Mo{S}_2$