... In particular, the short-range magnetic order at temperatures above the magnetic-transition p... more ... In particular, the short-range magnetic order at temperatures above the magnetic-transition point is not completely destroyed (in the two-dimensional case it is retained at temperatures up to T $jJ j), so that there exists a wide temperature range T > TM with a strong short-range ...
A generalized supersymmetric representation of the Hubbard operator algebra is considered. This r... more A generalized supersymmetric representation of the Hubbard operator algebra is considered. This representation is applied to the infinite-U Hubbard model. A mean-field theory which takes into account both on-site and inter-site virtual boson-fermion transitions is developed. Unlike previous approaches, the mean-field theory considered is free from divergences. Possible application of these results to the ferromagnet-paramagnet transition, as well as to other problems is discussed.
We consider formulations of the functional renormaliztion-group flow for correlated electronic sy... more We consider formulations of the functional renormaliztion-group flow for correlated electronic systems, having the dynamical mean-field theory as a starting point. We classify the corresponding renormalization-group schemes into those neglecting the one-particle irreducible (with respect to the local Green functions) six-point vertices and neglecting one-particle reducible six-point vertices. The former class is represented by the recently introduced DMF 2 RG approach [Phys. Rev. Lett. 112, 196402 (2014)], but also by the scale-dependent generalization of the one-particle irreducible (with respect to local Green functions, 1PI-LGF) representation of the generating functional [Phys. Rev. B 88, 115112 (2013)]. The second class is represented by the fRG flow within the dual fermion (DF) approach [Phys. Rev. B 77, 033101 (2008); ArXiv 1411.1342]. We compare formulations of fRG approach in each of these cases and suggest their further application to study 2D systems within the Hubbard mo...
The book is devoted to describing theoretical approaches to magnetism of two-dimensional systems:... more The book is devoted to describing theoretical approaches to magnetism of two-dimensional systems: mean-field theory, spin-fermion model, renormalization-group approach, and dynamic vertex approximation. Starting from the classical approaches by Stoner and Overhauser, but pointing the attention of the reader to their peculiarities in application to low-dimensional systems, described by the Hubbard model, the authors consider then the effect of magnetic fluctuations in these systems. Using the abovementioned approaches, the phase diagrams and magnetic properties of itinerant systems are analyzed in details. The book contains many results obtained by the authors, together with the overview of other existing approaches. It can be ordered from the authors (write by E-mail please).
... In particular, the short-range magnetic order at temperatures above the magnetic-transition p... more ... In particular, the short-range magnetic order at temperatures above the magnetic-transition point is not completely destroyed (in the two-dimensional case it is retained at temperatures up to T $jJ j), so that there exists a wide temperature range T > TM with a strong short-range ...
A generalized supersymmetric representation of the Hubbard operator algebra is considered. This r... more A generalized supersymmetric representation of the Hubbard operator algebra is considered. This representation is applied to the infinite-U Hubbard model. A mean-field theory which takes into account both on-site and inter-site virtual boson-fermion transitions is developed. Unlike previous approaches, the mean-field theory considered is free from divergences. Possible application of these results to the ferromagnet-paramagnet transition, as well as to other problems is discussed.
We consider formulations of the functional renormaliztion-group flow for correlated electronic sy... more We consider formulations of the functional renormaliztion-group flow for correlated electronic systems, having the dynamical mean-field theory as a starting point. We classify the corresponding renormalization-group schemes into those neglecting the one-particle irreducible (with respect to the local Green functions) six-point vertices and neglecting one-particle reducible six-point vertices. The former class is represented by the recently introduced DMF 2 RG approach [Phys. Rev. Lett. 112, 196402 (2014)], but also by the scale-dependent generalization of the one-particle irreducible (with respect to local Green functions, 1PI-LGF) representation of the generating functional [Phys. Rev. B 88, 115112 (2013)]. The second class is represented by the fRG flow within the dual fermion (DF) approach [Phys. Rev. B 77, 033101 (2008); ArXiv 1411.1342]. We compare formulations of fRG approach in each of these cases and suggest their further application to study 2D systems within the Hubbard mo...
The book is devoted to describing theoretical approaches to magnetism of two-dimensional systems:... more The book is devoted to describing theoretical approaches to magnetism of two-dimensional systems: mean-field theory, spin-fermion model, renormalization-group approach, and dynamic vertex approximation. Starting from the classical approaches by Stoner and Overhauser, but pointing the attention of the reader to their peculiarities in application to low-dimensional systems, described by the Hubbard model, the authors consider then the effect of magnetic fluctuations in these systems. Using the abovementioned approaches, the phase diagrams and magnetic properties of itinerant systems are analyzed in details. The book contains many results obtained by the authors, together with the overview of other existing approaches. It can be ordered from the authors (write by E-mail please).
Uploads
Papers by A. Katanin