Presentation - Conference Presentation

English

Toschi, Alessandro 

E138-02 - Forschungsbereich Correlations: Theory and Experiments 

Jul-2023

Workshop "Correlations in Novel Quantum Materials" 2023 

24-Jul-2023 - 28-Jul-2023

Stuttgart, Germany

dynamical mean field theory; Hubbard model; magnetism

Quantum phase transitions and collective modes: I 5868-N (FWF - Österr. Wissenschaftsfonds) 

Our perception of the natural world is significantly shaped by the properties of the detection process considered. One crucial aspect is the timescale of the probing mechanism: If this is larger than the typical timescales of the phenomenon under investigation, only averaged information will be gained. I will illustrate the importance of this aspect for the comparison of experimental observations and theoretical calculations of correlated quantum materials, by hands of an ab-initio+dynamical mean-field study [1] of the on-site magnetic fluctuations in several Fe-bases pnictides and chalcogenides. In this respect, I will also highlight the pivotal role played by vertex corrections in driving the slowing-down of the temporal magnetic fluctuations, as it occurs, e.g., in the proximity of Mott-Hubbard/Hund's-Mott metal-to-insulator transitions and of quantum critical points. Further, I will examine the situations in which the information encoded in the dynamical correlation functions does not completely vanish even in the infinite-time limit, by hands [2] of exact-diagonalization and dynamical mean-field calculations of Hubbard rings and of the Hubbard model, respectively. This analysis will illustrate how to link the asymptotic long-time response of correlated electrons to intrinsic features of the underlying (exact) many-particle energy spectrum, as well as, perspectively, to the entropy of the system under consideration.

Quantum Many-body Systems Physics: 70%
Computational Materials Science: 30%

1030 - Physik, Astronomie: 100%