Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 33: CE: Metal-Insulator Transition 1
TT 33.7: Vortrag
Mittwoch, 16. März 2011, 12:15–12:30, HSZ 105
LDA+DMFT study of (Sr, Ca)n+1RunO3n+1 ruthenates — •Evgeny Gorelov and Eva Pavarini — IFF and IAS, Forschungszentrum Jülich, 52425 Jülich
The ruthenates of the Ruddelsen-Popper series (Sr, Ca)n+1RunO3n+1 are unique among transition-metal oxides: changes in the number of RuO2 layers, Sr/Ca content and temperature lead to a variety of different properties, ranging from Mott insulating behavior and orbital order to metallic ferro- and meta- magnetism.
In order to understand how structural changes affect the properties, we perform and LDA+DMFT calculations for material-specific Hubbard models describing the partially filled Ru 4d4 shells. Since the eg Ru bands are well above the Fermi level, we consider only the t2g bands. For n=3 the unit cell contains two inequivalent Ru atoms, thus for this system we perform six-orbital LDA+cDMFT calculations.
The LDA+cDMFT scheme used is based on the ab-initio NMTO downfolding procedure and a weak-coupling CT-QMC impurity solver with full rotationally-invariant Coulomb interaction. We use a self-energy matrix in orbital space - Σij.
We identify the main difference among the materials in a substantial rearrangement of Ru t2g occupations, controlled by the interplay between Coulomb repulsion, number of RuO2 layers n, which reflects effective dimensionality, and changes in the t2g crystal field.