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MA: Fachverband Magnetismus
MA 4: Bio- und molekularer Magnetismus
MA 4.4: Talk
Monday, March 7, 2016, 10:15–10:30, H33
Manipulation of the magnetic coupling in deposited molecular macrocycles — •Heike Herper and Barbara Brena — Department of Physics and Astronomy, Uppsala University, Sweden
We present a first principles study focussing on the manipulation of the magnetic coupling of Fe phthalocyanine (FePc) deposited on metallic substrates. FePc couples FM to a Co(001) substrate. The coupling can be reversed by an O adlayer but the calculated coupling energies are large. [1] To overcome this problem higher coverages have been used. As in a spin valve the magnetization of the lower molecule is fixed by the FM film and the coupling between the molecules can vary. For (FePc)2 on Co(001) the coupling is 5 times smaller than for FePc/O/Co(001). To reverse the sign of the coupling different axial ligands have been used. A Cl ligand attached to (FePc)2 reverses the sign of the intermolecular coupling. Depending on the ligand also the spin state of the ligand may change [2].
To eliminate the molecule-substrate coupling FePc has been deposited on nonmagnetic Cu(001). The exchange coupling in (FePc)2 on Cu(001) turns out to be weaker as in the free (FePc)2 and is accompanied by a significant charge transfer.
All calculations have been performed using the VASP code and a Hubbard U on Fe. The U for the free molecule has been calculated within linear response as implemented in QUANTUM ESPRESSO.
[1] D. Klar et al., Phys Rev B 88, 224424 (2013)
[2] B. Brena and H. C. Herper, J. Appl. Phys. 117, 17B318 (2015)