Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 73: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles V (jointly with TT)

O 73.10: Vortrag

Donnerstag, 29. März 2012, 18:30–18:45, HE 101

Critical properties of the half-filled Hubbard model in three dimensions — •Georg Rohringer¹, Alessandro Toschi¹, Andrey Katanin², and Karsten Held¹ — ¹Institute for Solid State Physics, Vienna University of Technology 1040 Vienna, Austria — ²Institute of Metal Physics, Ekaterinburg, Russia

By means of the dynamical vertex approximation(DΓA) [1] we include spatial correlations on all length scales beyond the dynamical mean field theory (DMFT) for the half-filled Hubbard model in three dimensions. The most relevant changes due to non-local fluctuations are [2]: (i) a deviation from the mean-field critical behavior with the same critical exponents as for the three dimensional Heisenberg (anti)-ferromagnet and (ii) a sizable reduction of the Néel temperature (T_N) by ∼ 30% for the onset of antiferromagnetic order. Finally, we give a quantitative estimate of the deviation of the spectra between DΓA and DMFT in different regions of the phase-diagram.

[1] A. Toschi, A. Katanin, and K. Held, PRB 75, 045118 (2007).

[2] G. Rohringer, A. Toschi, A. Katanin, and K. Held, PRL in press [arXiv:1104.1919].