Table of contents

This review discusses the generalization of dynamical mean-field theory (DMFT) for strongly correlated electronic systems to include additional interactions necessary for the correct description of physical effects in such systems. Specifically, the additional interactions include: (1) the interaction of electrons with antiferromagnetic (or charge) order-parameter fluctuations in high-temperature superconductors leading to the formation of a pseudogap state; (2) scattering on static disorder and its role in the general picture of the Anderson-Hubbard metal-insulator transition, and (3) electron-phonon interaction and the features of electronic spectra in strongly correlated systems. The proposed DMFT+ approach incorporates the above interactions by introducing into the general DMFT model an additional (generally momentum-dependent) self-energy which is calculated in a self-consistent way without violating the general structure of the DMFT iteration cycle. The paper formulates a general calculational scheme for both one-particle (spectral functions and densities of states) and two-particle (optical conductivity) properties. The problem of pseudogap formation is examined, including Fermi arc formation and partial destruction of the Fermi surface, as are the metal-insulator transition in the disordered Anderson-Hubbard model, and the general picture of kink formation in the electronic spectra of strongly correlated systems. A generalization of the DMFT+ approach to realistic materials with strong electron-electron correlations is presented based on the LDA+DMFT method. The general model of the LDA+DMFT method is reviewed, as are some of its applications to real systems. The generalized LDA+DMFT+ approach is employed to calculate pseudogap states in electron- and hole-doped HTSC cuprates. Comparisons with angle-resolved photoemission spectroscopy (ARPES) results are presented.

Stratified two-component media (for example, sea water) can have general hydrothermodynamic properties widely different from the properties of 'usual' fluids, whose density depends on temperature only. For example, temperature perturbations in such media can increase despite a hydrostatically stable density stratification. In this review, a number of recently discovered physical mechanisms and phenomena are discussed, including the mechanisms of convective instability, the hydrodynamic 'memory' of two-component media, the formation of temperature and admixture concentration jumps, the anomalous response of binary mixtures to mechanical and thermal forcing, and the effective 'negative heat capacity'.

We review the current state of research into the development of nanomechanical resonators and their application as components of nanoelectromechanical and optomechanical systems for the highly sensitive detection and visualization of material structure. Methods for the manufacture and characterization of nanoscale mechanical resonators are described. We discuss quantum properties of nanomechanical resonators and dynamical cooling schemes for suppressing fluctuations in order to increase the threshold sensitivity of optomechanical and electromechanical systems.

A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) was held in the conference hall of the P N Lebedev Physical Institute, RAS on 26 October 2011.

The following reports were put on the session's agenda posted on the website www.gpad.ac.ru of the RAS Physical Sciences Division:

(1) Morozov S V (Institute of Microelectronics Technology and High Purity Materials, RAS, Chernogolovka, Moscow region) "New effects in graphene with high carrier mobility";

(2) Volostnikov V G (Samara Branch of the P N Lebedev Physical Institute, RAS, Samara) "Modern optics of Gaussian beams";

(3) Mushnikov N V (Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg) "Intermetallide-based magnetic materials".

The papers written on the base of these reports are published below. • New effects in graphene with high carrier mobility, S V Morozov Physics-Uspekhi, 2012, Volume 55, Number 4, Pages 408–412 • Modern optics of Gaussian beams, V G Volostnikov Physics-Uspekhi, 2012, Volume 55, Number 4, Pages 412–420 • Intermetallide-based magnetic materials, N V Mushnikov Physics-Uspekhi, 2012, Volume 55, Number 4, Pages 421–425