University of Minnesota
School of Physics & Astronomy
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Oriol T. Valls

Spin-Controlled Superconductivity and Tunable triplet Correlations in Graphene Nanostructures
K. Halterman, O.T. Valls, and M. Alidoust, Phys. Rev. Lett. 111, 046602 (2013)

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We study graphene ferromagnet/superconductor/ferromagnet (F/S/F) nanostructures via a microscopic self-consistent Dirac Bogoliubov-de Gennes formalism. We show that as a result of proximity effects, experimentally accessible spin switching phenomena can occur as one tunes the Fermi level $\mu_F$ of the F regions or varies the angle $\theta$ between exchange field orientations. Superconductivity can then be switched on and off by varying either $\theta$ or $\mu_F$ (a spin-controlled superconducting graphene switch). The induced equal-spin triplet correlations in S can be controlled by tuning $\mu_F$, effectively making a graphene based two-dimensional spin-triplet valve.