Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 108: Electron-Driven Processes at Surfaces and Interfaces

O 108.4: Talk

Thursday, March 19, 2020, 15:45–16:00, TRE Ma

Mechanism of ultrafast, spin-dependent electron transfer on ferromagnetic interfaces: an ab initio study — •Simiam Ghan, Karsten Reuter, and Harald Oberhofer — Chair of Theoretical Chemistry, Technical University of Munich, Garching, Germany.

Using ab-initio calculations, we explore the mechanism behind an observed spin-dependent electron transfer from photoexcited Argon monolayers into ferromagnetic substrates Fe(110), Ni(111) and Co(0001). A generalized Fermi golden rule is used to calculate transfer rates for majority and minority electrons from donor to acceptor-localized diabatic states. The diabatic states are created through partial diagonalization of the Kohn-Sham Hamiltonian, which also yields inter-state couplings. A faster transfer of minority (down) spins is predicted for Fe and Co substrates, as well as nonpreferential transfer for Ni - all in excellent agreement with ultrafast core-hole clock spectroscopic measurements.

The scheme allows us to compare the roles of donor-acceptor couplings and acceptor density of states in determining a final preferential spin transfer, and highlights the importance of the spacial character of participating states for spin transport on interfaces. Initial applications to self-assembled monolayers of organic molecules are discussed, with the prospect of predicting tunable electron (spin) transport behavior for e.g. organic spintronic devices.