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MA: Fachverband Magnetismus

MA 27: Electron Theory of Magnetism and Correlations

MA 27.4: Vortrag

Mittwoch, 29. März 2023, 10:15–10:30, HSZ 403

The role of non-local Coulomb interaction on spin models in the Hubbard limit — •Wejdan Beida, Markus Hoffmann, Juba Bouaziz, and Stefan Blügel — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA,52425 Jülich Germany

We extend the derivation of model spin Hamiltonians by including the non-local Coulomb interaction in the multi-band Hubbard model. We use Löwdin partitioning as the downfolding method of the dynamical electronic degrees of freedom described in the extended Hubbard model at half filling into low energy spin corner. The ground state of spin systems has been perturbatively corrected up to fourth order in the hopping parameter of the Hubbard model. The role which the non-local Coulomb interaction plays is strengthening the magnetism of the ground state. More importantly, it increases the importance of higher-order spin interactions beyond Heisenberg; Biquadratic, Four-spin, and Three-spin interactions. Generally speaking, this is confirmed by spin lattices with a site total spin in the range 1/2 * S * 3/2. For S = 1/2, we characteristically investigate the effect of next nearest neighbour hopping and inter-site Coulomb interaction on spin models for square and hexagonal lattice geometries.