We kindly invite to seminar in the framework of Modern Trends in Physics Research: Wednesday, **April 17, 2019** at 13:00 in room 16, Faculty of Physics AMU. SPEAKER:** Dr Konrad J. Kapcia.** AFFILIATION: Department of Computational Materials Science, Institute of Nuclear Physics, Polish Academy of Sciences, Kraków TITLE: **Exact phase diagram of the infinite-dimensional extended Falicov-Kimball model**.

ABSTRACT:

The
Falicov-Kimball model [1] is a simplified version of the Hubbard model
[2], where only electrons with, e.g., spin down are itinerant and the
other are localized. During the seminar, we will discuss results for the
extended Falicov-Kimball model at half-filling on the Bethe lattice in
the limit of large dimensions derived within the DMFT formalism [3-7],
which is a rigorous approach in this limit. The on-site and the
intersite density-density interactions between particles occupying
neighboring sites are included in the hamiltonian [5-7]. We determined
the exact phase diagrams of the model both in the ground state [6] and
at finite temperatures [7]. Using analytical formulas we showed that in
the ground state the system is an insulator for any non-zero values of
the interaction couplings and we detected the discontinuous transition
between two different charge-ordered phases [6]. The finite temperature
diagrams are a generalization of the diagram previously obtained in Ref.
[4] for the standard Falicov-Kimball model, but they are much richer
than it. In particular, it turns out that these diagrams contain more
types of ordered phases, both conductive and insulating, and phase
transitions between them are either continuous or discontinuous [7].
What is more, it turns out that in a certain range of interaction
parameters the order-disorder phase transition may be discontinuous.

[1]
L.M. Falicov, J.C. Kimball, Phys. Rev. Lett. 22, 997 (1969); R.
Ramirez, L.M. Falicov, J.C. Kimball, Phys. Rev. B 2, 3383 (1970).

[2] J. Hubbard, Proc. R. Soc. London, Ser. A 276, 238 (1963).

[3]
J.K. Freericks, V. Zlatic, Rev. Mod. Phys. 75, 1333 (2003); A. Georges,
G. Kotliar, W. Krauth, M.J. Rozenberg, Rev. Mod. Phys. 68, 13 (1996).

[4] R. Lemański, K. Ziegler, Phys. Rev. B 89, 075104 (2014); S.R. Hassan, H.R. Krishnamurthy, Phys. Rev. B 76, 205109 (2007).

[5] P.G.J. van Dongen, D. Vollhardt, Phys. Rev. Lett. 65, 1663 (1990); P.G.J. van Dongen, Phys. Rev. B 45, 2267 (1992).

[6] R. Lemański, K.J. Kapcia, S. Robaszkiewicz, Phys. Rev B 96, 205102 (2017).

[7] K.J. Kapcia, R. Lemański, S. Robaszkiewicz, preprint, arXiv: 1903.08092 (2019).

[in ENGLISH]

Chair: MK

Upcoming seminars can be found at http://zon8.physd.amu.edu.pl/~miran/seminars.html

Sincerely yours,*Michał BanaszakMaciej KrawczykAdam Miranowicz*

Informację wprowadził/a: **Marek Nowak**

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