JETP Letters最新文献

A decrease in the Hall resistance ρ_yx(B) in high magnetic fields has been observed in HgTe/CdHgTe double quantum well heterostructures after reaching the quantum Hall effect phase with a filling factor of ν = 1, indicating a possible transition to a state with ν = 0. A comparison with the calculated Fermi level trajectories in the picture of Landau levels suggests that this decrease in ρ_yx(B) can be attributed to the mutual influence of the electron and hole states in this system. Correlations between the chiral trajectories of electrons and holes in the two layers of the double quantum well also likely contribute, since this effect has not been observed in identical heterostructures with a single HgTe quantum well.

The spectral and photophysical properties of two colorless compounds 2-(1,3-benzothiazol-2-yl)-bromophenol and N-[2-(4-oxo-3,4-dihydroquinazolin-2-yl)phenyl]naphthalene-2-sulfonamide with an anomalously large Stokes shift of luminescence have been investigated. The possibility of lasing with a potentially broad tuning of the spectral band in the green–yellow spectral region under pumping by the third harmonic of a Nd:YAG laser has been demonstrated in 2-(1,3-benzothiazol-2-yl)-bromophenol.

Within the framework of a stationary model of relativistic self-focusing, it is shown that the addition of a thin layer of denser plasma on the propagation axis of a circularly polarized beam increases the axial magnetic field generated by it via the inverse Faraday effect by more than a factor of 10 compared to the case of a homogeneous plasma. The magnitude of the axial field in this case can exceed the magnetic field of the laser wave, which makes it possible, at radiation intensities ~10²⁶ W/cm² potentially achievable in the near future, to approach the level of teragauss quasi-stationary fields.

Compounds with thiol groups play a key role as structural elements of self-assembled thiolate monolayers on the surface of noble metals. The process of formation of H₃CS–Au–SCH₃ and H₃CS–Ag–SCH₃ complexes on the Au(111) and Ag(111) surfaces has been studied using the classical molecular dynamics method. All possible energy barriers accompanying the formation of these complexes have been calculated. The anisotropy of diffusion barriers arising from the formation of methyl thiolate and an adsorbed gold atom on the reconstructed Au(111) surface has been demonstrated. In conclusion, the most probable mechanisms of formation of the H ₃CS–Au–SCH₃ and H₃CS–Ag–SCH₃ complexes have been analyzed.

The effect of 3-MeV electron irradiation at a fluence of 5 × 10¹⁸ cm^–2 on the thermal conductivity κ(T) of type IIa and type Ib high-pressure high-temperature diamond single crystals with nitrogen concentrations of less than 1 ppm and approximately 70 ppm, respectively, has been studied. Irradiation reduces the thermal conductivity κ(T) over the entire studied temperature range 5 K < T < 410 K. For pure diamond, the strongest decrease in κ(T) by a factor of 350 is observed at 25–30 K, but the thermal conductivity κ(T) at room temperature T = 300 K decreases by a factor of only 1.56. Compared to pure diamond, the thermal conductivity of irradiated doped diamond decreases much less strongly at low temperatures, but more strongly at T > 140 K. After irradiation, the difference in the reduction of the thermal conductivity between the two types of diamond is so large that κ(T) for doped diamond is larger than that for pure diamond at T < 50 K and is an order of magnitude larger at 5 K. Experimental data allow the assumption that the rate of phonon scattering by neutral radiation defects—vacancies, their aggregates, and Frenkel pairs (pairs of interacting interstitial atoms and vacancies)—in pure diamond is much higher than that by such negatively charged defects in nitrogen-doped diamond at low temperatures. However, the ratio of scattering rates becomes inverse at high temperatures.

We investigated laser-controlled polarization effects in high-harmonic generation from graphene quantum dots driven by intense arbitrary polarized laser fields, using a tight-binding framework. The polarization state of the emitted harmonics, including ellipticity and ellipse orientation, is characterized through the Stokes parameters. We revealed that elliptically polarized driving fields can generate harmonics with linear and elliptical polarizations, and conversely that harmonics with controlled ellipticity can emerge from linearly polarized excitation. Our numerical results demonstrated that the harmonic polarization can be effectively controlled by changing the polarization of the exciting laser field, without the need for additional control elements.

Low-temperature magnetotransport of thin epitaxial films of the topological semimetal SrIrO₃ grown on (110)Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PMN–PT) and (001)SrTiO₃ substrates, which induce tensile (ε = +1.5%) and compressive (ε = –1.4%) strains, respectively, has been studied. An anomalous Hall effect, which is caused by the presence of J_eff = 1/2 states in the electronic spectrum of the Berry curvature, has been detected in both films. The anomalous Hall effect has been observed for the first time in the SrIrO₃/PMN–PT film, where the epitaxial strain changes the sign of the Hall coefficient and significantly increases the anomalous Hall conductivity compared to the SrIrO₃/SrTiO₃ film. The behaviors of the magnetoresistance in the SrIrO₃/SrTiO₃ and SrIrO₃/PMN–PT films are qualitatively different. In the former film, the magnetoresistance is negative, has a magnitude of 3.3%, exhibits a V-shaped magnetic field dependence, and is described by a superposition of weak localization and a classical orbital background proportional to the square of the external magnetic field. In the latter film, the conductivity film exhibits a peak at zero external field, which is typical of weak antilocalization. Approximation of the magnetic-field dependence of the film resistance using the Maekawa–Fukuyama model with a quadratic magnetic field background yields a dephasing length of Lφ = 10–40 nm and a dephasing exponent of p ≈ 1, which corresponds to a two-dimensional Coulomb interaction between electrons. The sign of the epitaxial strain determines the type of quantum corrections to the conductivity (weak antilocalization or localization) and the magnitude of the anomalous Hall effect.

A strong magnetic field suppresses interlayer tunneling in layered conductors and leads to a transition from a quasi-three-dimensional to a quasi-two-dimensional electron regime. The influence of this quantum 3D‒2D crossover on the thermodynamic properties has been examined in this work taking into account the Zeeman splitting of spin states. It has been shown that orbital coherence suppression and the Zeeman effect jointly change the electron spectrum and redistribute the subband populations, leading to a nonmonotonic dependence of the magnetization on the magnetic field in the crossover region. In the high-field region, the system transitions to a spin-polarized state, and the magnetization saturates. The obtained results indicate the important role of spin effects in the formation of the response in the crossover region.

The acoustic antiresonance in the magnon dissipation spectrum of yttrium iron garnet films on a gadolinium gallium garnet substrate has been described. The frequency-dependent energy loss Γ( f ) of a uniform magnon mode due to the magnetoelastic interaction with standing acoustic modes of the substrate has been calculated using the Kubo formalism. It has been shown that the linear relationship between the condensate critical field and the energy loss Γ( f ) reproduces the positions and widths of the resonances but does not describe the deep asymmetric dips in the antiresonances. To ensure quantitative agreement with experiment, two nonlinear corrections have been introduced: the Bose–Einstein suppression of the phonon channel with an exponent of 5/2 and the Fano interference term, which describes quantum interference between the direct and resonant scattering channels. the effective temperature of the phonon bath T * ≈ 2.2 K, as well as the parameters of the Fano resonances, including the width γ_Fano ≈ 65 kHz and the asymmetry parameter q = –2.5, has been determined from the approximation of the experimental data. The proposed model explains all the observed features of dissipation and opens up the possibility of targeted control of the coherence time of magnon states by designing the phonon spectrum of the substrate.

X-ray beam scattering from a bent lateral crystal has been considered for three Bragg–Laue diffraction cases. An algorithm based on two-dimensional recurrence relations for dynamic diffraction has been developed to calculate distributions of the scattering intensity in the reciprocal space. Mapping has been numerically simulated depending on the X-ray beam illumination region of the side face and the top surface of the crystal. The diffracted X-ray intensity distribution inside the bent lateral crystal has been calculated for three cases.