Dresden 2020 – scientific programme
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MA: Fachverband Magnetismus
MA 30: Ultrafast Magnetization III
MA 30.9: Talk
Wednesday, March 18, 2020, 11:45–12:00, HSZ 101
A real-space tight-binding approach to model ultrafast spin dynamics in heterostructures — •Franziska Töpler1, Jürgen Henk1, and Ingrid Mertig1,2 — 1Martin Luther University Halle-Wittenberg, Halle, Germany — 2Max Planck Institute of Microstructure Physics, Halle, Germany
In the process of laser-induced ultrafast demagnetization hot spin-polarized electrons are excited. In a system with a magnetic/nonmagnetic interface they generate a spin current crossing this interface. Various origins of this spin current generation are discussed in literature, for example the spin-dependent Seebeck effect [1] or energy- and spin-dependent electron transmittance of the interface [2].
To obtain a better understanding of the underlying microscopic processes and the role of the interface we implemented a real-space tight-binding model. We follow the temporal evolution of occupation numbers, including perturbation by laser excitation, by solving the corresponding equations of motion. Interaction with the phonon system is incorporated as the coupling to a bath in form of Lindblad operators. In addition link currents are defined as intersite occupation flow in analogy to conventional charge and spin currents. We investigate these in model systems composed of magnetic and nonmagnetic sites and compare our results to experimental findings.
[1] Seifert et al., J. Phys. D: Appl. Phys. 51 (2018) 364003
[2] Alekhin et al., J. Phys.: Condens. Matter 31 (2019) 124002