Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Correlated Electrons: Theory 1
TT 28.2: Vortrag
Donnerstag, 8. September 2022, 09:45–10:00, H23
Fluctuations analysis of the spin susceptibility: Néel ordering revisited in dynamical mean field theory — •Georg Rohringer1 and Lorenzo Del Re2 — 1Institute of Theoretical Physic, University of Hamburg, 20355 Hamburg, Germany — 2Department of Physics, Georgetown University, 37th and O Sts., NW, Washington, DC 20057, USA
We revisit the antiferromagnetic (AF) phase diagram of the single-band three-dimensional Hubbard model on a simple cubic lattice studied within the dynamical mean field theory. Although this problem has been investigated extensively in the literature, a comprehensive understanding of the impact of the different one- and, in particular, two-particle local correlation functions of DMFT on the AF transition temperature is still missing. We have, hence, performed a fluctuation analysis of TN with respect to different local bosonic fluctuations (charge, spin, particle-particle) contained in the two-particle vertex of DMFT. Our results indicate that, beyond weak coupling, the screening of the DMFT vertex by local fluctuations leads to an enhancement of TN with respect to a random phase approximation (RPA) like calculation where this vertex is replaced by the bare interaction. The overall suppression of TN in DMFT with respect to RPA is then solely due to the incoherence introduced by the DMFT self-energy in the one-particle Green’s functions. This illustrates the Janus-faced role of the local moment formation in the DMFT solution of the Hubbard model, which leads to completely opposite effects in the one- and two-particle correlation functions.