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TT: Fachverband Tiefe Temperaturen

TT 43: Correlated Electrons: Metal-Insulator Transition 2

TT 43.1: Vortrag

Donnerstag, 29. März 2012, 15:00–15:15, H 3010

Correlation effects in ruthenates: LDA+DMFT study — •Evgeny Gorelov and Eva Pavarini — IAS-3, Forschungszentrum Jülich, 52425 Jülich

The ruthenates of the Ruddlesden-Popper family A_n+1Ru_n O_3n+1 where A=(Sr, Ca) are unique among transition-metal oxides, because the change of cation A and/or in the number n of RuO₂ layers leads to a variety of collective phenomena, ranging from multi-band Mott transitions to ferro- and meta-magnetism. To understand these systems, it is necessary to disentangle the effects of Coulomb repulsion in the 4d⁴ Ru shell from those of lattice distortions and chemistry. By using the LDA+DMFT approach, we show how such disentanglement explains the nature of the metal-insulator transition in single-layered Ca ruthenates [1] and the evolution of electronic structure in n-layered Sr ruthenates [2]. We use LDA+DMFT scheme based on the N-th Order Muffin-Tin Orbital approach and the weak-coupling CT-quantum Monte Carlo method as impurity solver. This method allows us to take into account the full rotationally-invariant Coulomb interaction, as well as full on-site self-energy matrix in orbital space with spin-orbit coupling. We discuss changes in effective mass and orbital polarization as a result of spin-flip processes and spin-orbit interaction.
E. Gorelov et al., Phys. Rev. Lett. 104, 226401 (2010).
M. Malvestuto et al., Phys. Rev. B 83, 165121 (2011).