Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 64: Poster Session: Transport
TT 64.16: Poster
Donnerstag, 4. April 2019, 15:00–18:30, Poster D
Thermal-induced currents and spin caloritronics in a graphene nanostructure — •Thi Thu Phùng1,2, Andreas Honecker1, and Javad Vahedi1 — 1Laboratoire de Physique Théorique et Modélisation, CNRS UMR 8089, Université de Cergy Pontoise, 95302 Cergy-Pontoise, France — 2University of Science and Technology of Ha Noi, 18 Hoang Quoc Viet, Ha Noi, Vietnam
We study a spin caloritronics device based on a heterostructure consisting of a hexagonal graphene flake with anti-ferromagnetic zigzag edges as central region connecting two leads [1] using the non-Equilibrium Green’s Function (NEGF) technique combined with a mean-field approximation for the Hubbard model. Spin-up and spin-down currents are simultaneously generated and flow in opposite directions when leads are at different temperatures. Thanks to the magnetization at the zigzag-edges of the graphene flake, the resulting spin-up current is much larger such that both total spin current and net charge current are obtained. The key ingredients are the imbalance of charge carrier concentrations which is determined by the Fermi distribution at the source and drain, transmission spectra and on-site Coulomb repulsion U. These currents not only exhibit a negative differential thermoelectric resistance, but also can be modulated easily by the gate voltage. By adjusting parameters suitably, the efficiency of the spin-filtering effect might achieve nearly 100%. These findings make the proposed device a promising candidate for spin caloritronics applications.
[1] A. Valli, A. Amaricci, V. Brosco, and M. Capone, Nano letters 18, 2158 (2018).