Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 55: Electron theory and micromagnetism

MA 55.6: Talk

Friday, April 5, 2019, 10:45–11:00, H38

Broken symmetry states of magnetic molecular complexes — •Yaroslav Pavlyukh, Wolfgang Huebner, and Georgios Lefkidis — Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67653 Kaiserslautern, Germany

The broken-symmetry (BS) approach is broadly used to extract the magnetic properties of many-body systems from a DFT calculation. However, there is an ambiguity in the nature of the underlying electronic states and the corresponding spin densities: the spin density from DFT is not a well-defined property and the Kohn-Sham determinants need not be eigenfunctions of the square of the total spin (Ŝ²).

Here we propose a procedure, in which the detailed analysis of a redundant number of electronic many-body excitations gives insight into the intrinsic magnetic properties of the system. We perform highly correlated multi-determinant calculations on two prominent synthesized and characterized metallacrown molecules with frustrated antiferromagnetic order driven by the superexchange mechanism, i.e., {CuCu₄} and {CuFe₄} [1]. For those we unambiguously show that the BS states are not eigenstates of Ŝ² and, in addition, theoretically compute several magnetic (exchange coupling J [2]) and relativistic properties (g-tensors), which we find to be in close agreement with experiment.

• [1] Y. Pavlyukh, E. Rentschler, H. J. Elmers, W. Hübner, and G. Lefkidis, Phys. Rev. B 97, 214408 (2018)
• [2] W. Hübner, Y. Pavlyukh, G. Lefkidis, and J. Berakdar, Phys. Rev. B 96, 184432 (2017)