Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 10: Correlated Electrons: (General) Theory 1

TT 10.8: Vortrag

Montag, 26. März 2012, 17:00–17:15, H 3010

Orbital and magnetic order in the infinite-dimensional two-band Hubbard model — •Ernst von Oelsen, Götz Seibold, and Jörg Bünemann — Lehrstuhl Computational Physics, BTU Cottbus, Postfach 101344, 03013 Cottbus

Based on the time-dependent Gutzwiller approximation (GA), generalized to the case of multiple bands [1,2], we investigate the stability of magnetic and orbital order in the infinite dimensional two-band Hubbard model. Contrary to the Hartree-Fock plus random-phase approximation, the incorporation of the local multiplet-structure within our approach leads to a much larger sensitivity of ferromagnetism on the the ratio between Hund coupling and intra-orbital repulsion J/U. Besides, we find that the Brinkman-Rice localization transition, which in the paramagnetic GA appears at integer doping is always masked by an antiferromagnetic (for two particles per site) or an orbitally ordered (for one particle per site) ground state. In addition, at larger values of J/U a quantum Lifshitz point is found where ferro-, para- and incommensurate magnetic phases meet.
E. von Oelsen, G. Seibold, and J. Bünemann, New J. Phys. 13, 113031 (2011).
E. v. Oelsen, G. Seibold, and J. Bünemann, Phys. Rev. Lett. 107, 076402 (2011).