Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 16: Bio- and Molecular magnetism

MA 16.5: Vortrag

Dienstag, 17. März 2015, 10:30–10:45, EB 202

Magnetic coupling in unligated and ligated FePc sandwiches — •Heike C. Herper and Barbara Brena — Department of Physics and Astronomy, Uppsala University, Sweden

Molecular magnetic materials are intensively discussed as candidates for future electronic devices however switching the spin state or changing the magnetic coupling is still a challenging task. We have performed an ab initio study of the magnetic and structural properties of sandwiches of FePc molecules which serve as a model system for transition metal based Pc complexes. Investigations include molecules in gas phase as well as adsorbed on a metal substrate. The two FePc molecules are weakly bonded and the calculated exchange coupling is smaller than 20 meV such that a flipping from ferromagnetic (FM) to antiferromagnetic (AF) coupling can be achieved. The magnetic coupling can be even more reduced (< 1meV) by ligating the two FePc molecules with Cl whereby the ground state configuration changes from FM to AF. If the unligated (FePc)₂ is deposited on a Co(001) substrate the lower FePc couples in agreement with previous findings [1,2] FM to the Co film but the intermolecular coupling switches from FM to AF whereby the coupling strength is similar to the one of the free (FePc)₂.

[1] D. Klar et al., Phys. Rev. B 88, 224424 (2013)
H. C. Herper et al., Phys. Rev. B 89, 085411 (2014)