We address thermal and strength phenomena occurring in metal nanoparticles due to excitation of surface plasmons. The temperature of the nanoparticle is found as a function of the plasmon population, allowing for the Kapitza heat boundary resistance and temperature dependencies of the host dielectric heat conductivity and the metal electrical conductivity. The latter is shown to result in the positive thermal feedback which leads to appearance of the maximum possible number of plasmon quanta in the steady-state regime. In the pulsed regime the number of plasmon quanta is shown to be restricted from above also by the ponderomotive forces, which tend to deform the nanoparticle. Obtained results provide instruments for the heat and strength management in the plasmonic engineering.

Temperature dependences of low field Hall resistivity H are used to separate anomalous (a H) and nor- mal (RHB) contributions to Hall effect in chiral magnet MnSi (Tc 29.1K). It is found that the transition between paramagnetic (T > Tc) and magnetically ordered (T < Tc) phases is accompanied by the change inanomalous Hall resistivity from low temperature behavior governed by Berry phase effects (aH = μ0S22M,T < Tc) to high temperature regime dominated by skew scattering (aH = μ0S1M, T > Tc). The crossover between the intrinsic (2) and extrinsic () contributions to anomalous Hall effect develops together with the noticeable increase of the charge carriers’ concentration estimated from the normal Hall coefficient (from n/nMn(T > Tc) 0.94 to n/nMn(T < Tc) 1.5, nMn 4.2 · 1022 cm−3). The observed features may corre- spond to the dramatic change in Fermi surface topology induced by the onset of long range magnetic order in MnSi.

We report results of the high frequency (60GHz) electron spin resonance (ESR) study of the quantum criti- cal metallic system Mn1−xFexSi. The ESR is observed for the first time in the concentration range 0 < x < 0.24 at temperatures up to 50K. The application of the original experimental technique allowed carrying out line shape analysis and finding full set of spectroscopic parameters, including oscillating magnetization, line width and g factor. The strongest effect of iron doping consists in influence on the ESR line width and spin relaxation is marked by both violation of the classical Korringa-type relaxation and scaling behavior. Additionally, the non-Fermi-liquid effects in the temperature dependence of the ESR line width, which may be quantitatively described in the theory of W¨olfle and Abrahams, are observed at quantum critical points x 0.11 and xc 0.24.

We show that experimentally observed complex line shapes of smeared Van Hove singularities in the resistivity of a quasi-one-dimensional system may be due to non-Born effects in scattering. At low concentration of impurities with respect to scattering amplitude λ the non-Born effects are essential if the Fermi level is sufficiently close to singularity. The structure of the line shape depends on the sign of λ: for repulsion (λ>0) it is "plateau-minimum-maximum-plateau", while for attraction (λ<0) it is "plateau-maximum-minimum-maximum-plateau". In contrast with Fano-resonance scenario, complex structure of the line shape arises even in the absence of a resonant level.

Tunneling differential conductivity (or resistivity) is a sensitive tool to experimentally test the non-Fermi liquid behavior of strongly correlated Fermi systems. In the case of common metals the Landau-Fermi liquid theory demonstrates that the differential conductivity is a symmetric function of bias voltage V. This is because the particle-hole symmetry is conserved in the Landau-Fermi liquid state. When a strongly correlated Fermi system turns out to be near the topological fermion condensation quantum phase transition, its Landau-Fermi liquid properties disappear so that the particle-hole symmetry breaks making the differential tunneling conductivity to be asymmetric function of V. This asymmetry can be observed when a strongly correlated metal is in its normal, superconducting or pseudogap states. We show that the asymmetric part of the dynamic conductance does not depend on temperature provided that the metal is in its superconducting or pseudogap states. In normal state the asymmetric part diminishes at rising temperatures. Under the application of magnetic field the metal transits to the Landau-Fermi liquid state and the differential tunneling conductivity becomes a symmetric function of V. These findings are in good agreement with recent experimental observations.

The energy losses due to Cherenkov emission of magnons during the interaction of a slow heavy monopole with magnetically ordered media are discussed.

The results obtained in the works supported in part by the Russian Foundation for Basic Research (project 12-02-00594) are briefly reviewed. We mainly focus on interrelations between classical integrable systems, Painlevé-Schlesinger equations and related algebraic structures such as classical and quantum R-matrices. The constructions are explained in terms of simplest examples. © 2015, Pleiades Publishing, Inc.

Theoretical studies are performed of planar cavity–polariton systems under resonant optical excitation. We show that if the cavity is spatially anisotropic, the polariton spin is highly sensitive to the pump polarization direction, which can be used to modulate the circular polarization of the output light. In particular, when the right- and left-circular components of the incident wave have equal intensities and mutually opposite angular momenta, the pump has strictly linear yet angle-dependent polarization and as such brings about a periodic angular variation of the polariton spin. Free motion of polaritons is the other factor determining the shape of the cavity-field distribution. Such externally driven and highly tunable spin patterns represent a counterpart of spin shaping in nonresonantly excited Bose-Einstein condensates of cavity polaritons.

We present direct measurements of the superconducting order parameter in nearly optimal FeSe Te single crystals with the critical temperature *T*C ≈ 14 K. Using the intrinsic multiple Andreev reflection effect (IMARE) spectroscopy and measurements of the lower critical field, we directly determined two superconducting gaps, ΔL ≈ 3.3−3.4 meV and ΔS ≈ 1 meV, and their temperature dependences. We show that a twoband model fits well the experimental data. The estimated electron–boson coupling constants indicate a strong intraband and a moderate interband interaction.

The electron-hole liquid (EHL) in SiGe layers of Si/Si1 − *x* Ge *x* /Si quantum-confinement heterostructures is discovered. It is composed of quasi-two-dimensional holes in the quantum well formed by the SiGe layer and quasi-three-dimensional electrons, which occupy a wider region of space centered on this layer. The densities of electrons and holes in the EHL are determined to be*p* 0 ≈ 8.5 × 1011 cm−2 and *n* 0 ≈ 4.8 × 1018 cm−3, respectively. It is demonstrated that the gas phase consists of excitons and excitonic molecules. The conditions on the band parameters of the structure under which the formation of the EHL of this kind and biexcitons is possible are formulated.

The phonon and electronic properties, the Eliashberg function and the temperature dependence of resistance of electride Ca2N are investigated by the DFT-LDA (density functional theory in local density approximation) plane-wave method. The phonon dispersion, the partial phonon density of states and the atomic eigenvectors of zero-center phonons are studied. The electronic band dispersion and partial density of states conclude that Ca2N is a metal and the Ca 3p, 4s and N 2p orbitals are hybridized. For the analysis of an electron-phonon interaction and its contribution of the Eliashberg function to resistance was calculated and a temperature dependence of resistance due to electron-phonon interaction was found.

We analyze the entanglement spectrum of superfluid phases of $^3$He, the 3D B-phase and the planar phase in two dimensions. We find explicitly the wave functions of the low-lying eigenstates, including Majorana zero modes, as well as the corresponding part of the spectrum of the entanglement Hamiltonian.

The spin polarization features of an electron system and the relaxation of nonequilibrium spin excitations near an even-denominator fractional state of 3/2 in a two-dimensional electron system based on the GaAs/AlGaAs heterostructure are experimentally investigated. It is shown that the 3/2 state is a singular point in the filling factor dependence of the spin ordering of the two-dimensional electron system, at which the spin subsystem is rearranged. A giant slowing down of the relaxation of spin excitations to the ground state is revealed in a certain range of filling factors near filling factor 3/2.

We investigated the tunneling cureent peculiarities in the system of two coupled by means of the external ﬁeld quantum dots (QDs) weakly connected to the electrodes in the presence of Cou lomb correlations. It was found that tuning of the Rabi frequency induces fast multiple tunneling current switching and leads to the negative tunneling conductivity. Special role of multi- electrons states was demonstrated . Moreover we revealed conditions for bistable behavior of the tunneling current in the coupled QDs with Coulomb correlations.

It was shown many years ago by Dijkgraaf, Velinde, and Verlinde for two-dimensional topological conformal field theory and more recently for the non-critical String theory that some models of these two types can be solved using their connection to the special case of Frobenius manifolds—the so-called Saito Frobenius manifolds connected to a deformed singularity. The crucial point for obtaining an explicit expression for the correlators is finding*the flat coordinates* of Saito Frobenius manifolds as functions of the parameters of the deformed singularity. We suggest a direct way to find the flat coordinates, using the integral representation for the solutions of the Gauss–Manin system connected to the corresponding Saito Frobenius manifold for the singularity.

The possibility of the generation of quasi-cw terahertz radiation by the optical rectification method for broad-band Fourier unlimited nanosecond laser pulses has been experimentally demonstrated. The broadband radiation of a LiF dye-center laser is used as a pump source of a nonlinear optical oscillator. The energy efficiency of terahertz optical frequency conversion in a periodically polarized lithium niobate crystal is 4 × 10^{−9 at a pump power density of 7 MW/cm2}

We propose potential geometry for fabrication of the graphite sheets with atomically smooth edges. For such sheets with Bernal stacking, the electron-electron interaction and topology should cause sufficiently high density of states resulting in the high temperature of either spin ordering or superconducting pairing.