Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Graphene (joint session TT/DY/HL)

TT 13.6: Vortrag

Montag, 16. März 2020, 16:15–16:30, HSZ 201

Spin-caloritronic transport in hexagonal graphene nanodots — Thi Thu Phùng¹, Robert Peters², •Andreas Honecker¹, Guy Trambly de Laissardière¹, and Javad Vahedi^1,3 — ¹Laboratoire de Physique Théorique et Modélisation, CNRS (UMR 8089), Université de Cergy-Pontoise, France — ²Department of Physics, Kyoto University, Japan — ³Department of Physics and Earth Sciences, Jacobs University Bremen, Germany

First, we investigate magnetism in the Hubbard model for hexagonal graphene dots. Employing static respectively dynamic mean-field theory (DMFT) we show that magnetism can be generated at the zigzag edges beyond a critical interaction of the on-site Coulomb interaction U that decreases with increasing dot size. Building on these results, we apply the Landauer formalism in the framework of the non-equilibrium Green function method to calculate the spin and charge currents through these dots as a function of temperature. We show that in the “meta” configuration of a hexagonal dot subject to weak Coulomb interactions, a pure spin current can be driven just by a temperature gradient in a temperature range that is promising for device applications.