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TT: Fachverband Tiefe Temperaturen

TT 17: Poster Session Correlated Electrons 1

TT 17.9: Poster

Montag, 16. März 2020, 15:00–19:00, P2/EG

Interplay of spin-orbit coupling and spin-orbital super-exchange — •Pascal Strobel and Maria Daghofer — Institut für Funktionelle Materie und Quantentechnologien, Universität Stuttgart, 70550 Stuttgart, Germany

In strongly correlated materials with a t_2g⁴ electron configuration the interplay of superexchange, tetragonal crystal field splitting, and spin-orbit coupling is supposed to support a superposition of singlet and triplet states from the spin-orbit coupling Hamiltonian. This property is often referred to as excitonic magnetism. Ca₂RuO₄ is argued to be a promising candidate for hosting this excitonic magnetism by Raman scattering data [1] as well as numerical results from the variational cluster approach [2]. In order to get a comparison to neutron scattering data [3], we derive an effective hopping Hamiltonian via second order perturbation theory which gives rise to a Kugel-Khomskii type model. Using exact diagonalization we obtain spectra of the magnetic structure factor which show a high agreement with the experiment. With this model it is possible for us to investigate the influence of the parameters appearing in the Kugel-Khomskii type Hamiltonian in the regime of non zero spin-orbit coupling.

[1] Phys. Rev. Lett.119, 067201 (2017)

[2] arXiv:1910.13977v2 (2019)

[3] Phys. Rev. Lett.115, 247201 (2015)