Results for "S. Boldyrev"

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Turbulence without pressure in d dimensionsMay 16 1998Jun 29 1999The randomly driven Navier-Stokes equation without pressure in d-dimensional space is considered as a model of strong turbulence in a compressible fluid. We derive a closed equation for the velocity-gradient probability density function. We find the asymptotics ... More
On Batchelor passive advection by a finite-time correlated random velocity fieldJun 20 2000The Batchelor passive advection is an advection by a smooth velocity field. If the velocity field is a delta-correlated in time random Gaussian process, then the problem is reduced to quantum mechanics of fluctuating velocity gradient u'(t). For the finite-time ... More
Burgers turbulence with pressureJul 31 1997The randomly driven Burgers equation with pressure is considered as a 1D model of strong turbulence of compressible fluid. It is shown that infinitely small pressure provides a finite effect on the velocity and density statistics and this case therefore ... More
A note on Burgers' turbulenceOct 13 1996In this note the Polyakov equation [Phys. Rev. E {\bf 52} (1995) 6183] for the velocity-difference PDF, with the exciting force correlation function $\kappa (y)\sim1-y^{\alpha}$ is analyzed. Several solvable cases are considered, which are in a good agreement ... More
Integer Quantum Hall Transition and Random SU(N) RotationSep 14 2000We reduce the problem of integer quantum Hall transition to a random rotation of an N-dimensional vector by an su(N) algebra, where only N specially selected generators of the algebra are nonzero. The group-theoretical structure revealed in this way allows ... More
Nonlinear Magnetosonic Waves in a Multi-Ion-Species PlasmaNov 03 1997Magnetosonic waves are intensively studied due to their importance in space plasmas and also in fusion plasmas where they are used in particle acceleration and heating experiments. In the present paper we investigate the magnetosonic waves propagating ... More
On geometric properties of passive random advectionJul 27 1999We study geometric properties of a random Gaussian short-time correlated velocity field by considering statistics of a passively advected metric tensor. That describes universal properties of fluctuations of tensor objects frozen into the fluid and passively ... More
Turbulence in Magnetized Pair PlasmasMay 23 2018Alfv\'enic-type turbulence in strongly magnetized, low-beta pair plasmas is investigated. A coupled set of equations for the evolution of the magnetic and flow potentials are derived, covering both fluid and kinetic scales. In the fluid (MHD) range those ... More
Role of magnetic reconnection in MHD turbulenceDec 21 2016The current understanding of MHD turbulence envisions turbulent eddies which are anisotropic in all three directions. In the plane perpendicular to the local mean magnetic field, this implies that such eddies become current-sheet-like structures at small ... More
Collisionless Reconnection in Magnetohydrodynamic and Kinetic TurbulenceJul 19 2017It has recently been proposed (Loureiro & Boldyrev 2017; Mallet et al. 2017) that the inertial interval in magnetohydrodynamic (MHD) turbulence is terminated at small scales not by a Kolmogorov-like dissipation region, but rather by a new sub-inertial ... More
Velocity and velocity-difference distributions in Burgers turbulenceMay 10 2003Nov 01 2004We consider the one-dimensional Burgers equation randomly stirred at large scales by a Gaussian short-time correlated force. Using the method of dissipative anomalies, we obtain velocity and velocity-difference probability density functions and confirm ... More
Interstellar Scintillation of PSR J0437-4715 on Two ScalesApr 22 2002Mar 17 2006We sought to determine the scale of scintillation in the interstellar plasma of PSR J0437-4715. We used the Very Long Baseline Array to obtain scintillation amplitude and phase data, from dynamic spectra at 327 MHz. We observe two scales of scintillation ... More
Spectra and Growth Rates of Fluctuating Magnetic Fields in the Kinematic Dynamo Theory with Large Magnetic Prandtl NumbersMar 21 2001Mar 05 2002The existence of a weak galactic magnetic field has been repeatedly confirmed by observational data. The origin of this field has not as yet been explained in a fully satisfactory way and represents one of the main challenges of the astrophysical dynamo ... More
Scaling properties of small-scale fluctuations in magnetohydrodynamic turbulenceSep 09 2014Magnetohydrodynamic (MHD) turbulence in the majority of natural systems, including the interstellar medium, the solar corona, and the solar wind, has Reynolds numbers far exceeding the Reynolds numbers achievable in numerical experiments. Much attention ... More
Understanding of the role of magnetic fields: Galactic perspectiveFeb 20 2009A combination of observation, theory, modeling, and laboratory plasma experiments provides a multifaceted approach to develop a much greater understanding of how magnetic fields arise in galactic settings and how these magnetic fields mediate important ... More
Comment on the numerical measurements of the magnetohydrodynamic turbulence spectrum by A. Beresnyak (Phys. Rev. Lett. 106 (2011) 075001; MNRAS 422 (2012) 3495; ApJ 784 (2014) L20)Sep 29 2014The inertial-interval energy spectrum of strong magnetohydrodynamic (MHD) turbulence with a uniform background magnetic field was observed numerically to be close to $k^{-3/2}$ by a number of independent groups. A dissenting opinion has been voiced by ... More
Extending the Shakura-Sunyaev approach to a strongly magnetized accretion disc modelAug 21 2002Jun 16 2003We develop a model of thin turbulent accretion discs supported by magnetic pressure of turbulent magnetic fields. This applies when the turbulent kinetic and magnetic energy densities are greater than the thermal energy density in the disc. Whether such ... More
On the Spectrum of Magnetohydrodynamic TurbulenceMar 02 2005Jun 17 2005We propose a phenomenological model for incompressible magnetohydrodynamic turbulence. We argue that nonlinear-wave interaction weakens as the energy cascade proceeds to small scales, however, the anisotropy of fluctuations along the large-scale magnetic ... More
A Solvable Model for Nonlinear Mean Field DynamoMay 21 2001We formulate a solvable model that describes generation and saturation of mean magnetic field in a dynamo with kinetic helicity, in the limit of large magnetic Prandtl number. This model is based on the assumption that the stochastic part of the velocity ... More
Spectrum of magnetohydrodynamic turbulenceNov 10 2005Feb 24 2006We propose a phenomenological theory of strong incompressible magnetohydrodynamic turbulence in the presence of a strong large-scale external magnetic field. We argue that in the inertial range of scales, magnetic-field and velocity-field fluctuations ... More
Kolmogorov-Burgers Model for Star Forming TurbulenceAug 18 2001Oct 23 2001The process of star formation in interstellar molecular clouds is believed to be controlled by driven supersonic magnetohydrodynamic turbulence. We suggest that in the inertial range such turbulence obeys the Kolmogorov law, while in the dissipative range ... More
The Nature of Subproton Scale Turbulence in the Solar WindMay 13 2013The nature of subproton scale fluctuations in the solar wind is an open question, partly because two similar types of electromagnetic turbulence can occur: kinetic Alfven turbulence and whistler turbulence. These two possibilities, however, have one key ... More
A Model of Plasma Heating by Large-Scale FlowSep 29 2015Oct 02 2015In this work we study the process of energy dissipation triggered by a slow large scale motion of a magnetized conducting fluid. Our consideration is motivated by the problem of heating the solar corona, which is believed to be governed by fast reconnection ... More
Magnetic dynamo action in helical turbulenceNov 06 2007Dec 13 2007We investigate magnetic field amplification in a turbulent velocity field with nonzero helicity, in the framework of the kinematic Kazantsev-Kraichnan model. We present the numerical solution of the model for the practically important case of Kolmogorov ... More
Magnetic dynamo action in astrophysical turbulenceSep 03 2008Apr 11 2009We investigate the structure of magnetic field amplified by turbulent velocity fluctuations, in the framework of the kinematic Kazantsev-Kraichnan model. We consider Kolmogorov distribution of velocity fluctuations, and assume that both Reynolds number ... More
Scintillations and Levy flights through the interstellar mediumApr 09 2002Temporal broadening of pulsar signals results from electron density fluctuations in the interstellar medium that cause the radiation to travel along paths of different lengths. The Gaussian theory of fluctuations predicts that the pulse temporal broadening ... More
Amplification of magnetic fields by dynamo action in Gaussian-correlated helical turbulenceOct 16 2008We investigate the growth and structure of magnetic fields amplified by kinematic dynamo action in turbulence with non-zero kinetic helicity. We assume a simple Gaussian velocity correlation tensor, which allows us to consider very large magnetic Reynolds ... More
Magnetorotational Dynamo Action in the Shearing BoxApr 27 2017Magnetic dynamo action caused by the magnetorotational instability is studied in the shearing-box approximation with no imposed net magnetic flux. Consistent with recent studies, the dynamo action is found to be sensitive to the aspect ratio of the box: ... More
Non-Gaussian Radio-Wave Scattering in the Interstellar MediumJan 25 2005Feb 05 2006It was recently suggested by Boldyrev & Gwinn that the characteristics of radio scintillations from distant pulsars are best understood if the interstellar electron-density fluctuations that cause the time broadening of the radio pulses obey non-Gaussian ... More
On magnetic field generation in Kolmogorov turbulenceOct 28 2003Nov 26 2003We analyze the initial, kinematic stage of magnetic field evolution in an isotropic and homogeneous turbulent conducting fluid with a rough velocity field, v(l) ~ l^alpha, alpha<1. We propose that in the limit of small magnetic Prandtl number, i.e. when ... More
Coherent phonons in a $Bi_2Se_3$ film generated by an intense single-cycle THz pulseAug 10 2017Feb 24 2018We report an observation of coherent phonons of $E_g^1$, $E_u^1$, $A_{1g}^1$, and $E_g^2$ symmetry generated in a single-crystal film of $Bi_2Se_3$ by an intense single-cycle THz pulse. The atomic vibrations reveal themselves through periodic modulation ... More
Radio-wave propagation in the non-Gaussian interstellar mediumApr 29 2004Aug 02 2005Radio waves propagating from distant pulsars in the interstellar medium (ISM), are refracted by electron density inhomogeneities, so that the intensity of observed pulses fluctuates with time. The theory relating the observed pulse time-shapes to the ... More
Spectrum of Kinetic Alfven TurbulenceApr 26 2012A model for strong kinetic Alfv\'en plasma turbulence at scales smaller than the ion gyroscale is proposed. It is argued that magnetic and density fluctuations are concentrated mostly at two-dimensional structures, which leads to their Fourier energy ... More
Role of reconnection in inertial kinetic-Alfven turbulenceJan 29 2019In a weakly collisional, low-electron-beta plasma, large-scale Alfv\'en turbulence transforms into inertial kinetic-Alfv\'en turbulence at scales smaller than the ion microscale (gyroscale or inertial scale). We propose that at such kinetic scales, the ... More
Magnetohydrodynamic turbulence mediated by reconnectionJun 21 2017Magnetic field fluctuations in MHD turbulence can be viewed as current sheets that are progressively more anisotropic at smaller scales. As suggested by Loureiro & Boldyrev (2017) and Mallet et al (2017), below a certain critical thickness $\lambda_c$ ... More
Role of cross helicity in magnetohydrodynamic turbulenceJul 16 2008Jan 16 2009Strong incompressible three-dimensional magnetohydrodynamic turbulence is investigated by means of high resolution direct numerical simulations. The simulations show that the configuration space is characterized by regions of positive and negative cross-helicity, ... More
Magnetic dynamo action at low magnetic Prandtl numbersOct 31 2010Amplification of magnetic field due to kinematic turbulent dynamo action is studied in the regime of small magnetic Prandtl numbers. Such a regime is relevant for planets and stars interiors, as well as for liquid metal laboratory experiments. A comprehensive ... More
Levy model for interstellar scintillationsSep 23 2003Observations of radio signals from distant pulsars provide a valuable tool for investigation of interstellar turbulence. The time-shapes of the signals are the result of pulse broadening by the fluctuating electron density in the interstellar medium. ... More
On the Physics of Kinetic-Alfven TurbulenceMay 02 2013Observations reveal nearly power-law spectra of magnetic and density plasma fluctuations at subproton scales in the solar wind, which indicates the presence of a turbulent cascade. We discuss the three-field and two-field models for micro-scale plasma ... More
Numerical simulations of imbalanced strong magnetohydrodynamic turbulenceDec 04 2009Dec 07 2009Magnetohydrodynamics (MHD) is invoked to address turbulent fluctuations in a variety of astrophysical systems. MHD turbulence in nature is often anisotropic and imbalanced, in that Alfvenic fluctuations moving in opposite directions along the background ... More
On weak and strong magnetohydrodynamic turbulenceDec 13 2007Recent numerical and observational studies contain conflicting reports on the spectrum of magnetohydrodynamic turbulence. In an attempt to clarify the issue we investigate anisotropic incompressible magnetohydrodynamic turbulence with a strong guide field ... More
Turbulent Origin of the Galactic-Center Magnetic Field: Nonthermal Radio FilamentsDec 14 2005A great deal of study has been carried out over the last twenty years on the origin of the magnetic activity in the Galactic center. One of the most popular hypotheses assumes milli-Gauss magnetic field with poloidal geometry, pervading the inner few ... More
Calculations in the theory of tearing instabilitySep 03 2018Recent studies have suggested that the tearing instability may play a significant role in magnetic turbulence. In this work, we review the theory of the magnetohydrodynamic tearing instability in the general case of an arbitrary tearing parameter, which ... More
Strong magnetohydrodynamic turbulence with cross helicityApr 21 2010Magnetohydrodynamics (MHD) provides the simplest description of magnetic plasma turbulence in a variety of astrophysical and laboratory systems. MHD turbulence with nonzero cross helicity is often called imbalanced, as it implies that the energies of ... More
Spectrum of weak magnetohydrodynamic turbulenceJul 26 2009Turbulence of magnetohydrodynamic waves in nature and in the laboratory is generally cross-helical or non-balanced, in that the energies of Afv\'en waves moving in opposite directions along the guide magnetic field are unequal. Based on high-resolution ... More
Luminescent Ge-related centre in high-pressure synthesized diamondOct 20 2015We report on the high-pressure synthesis of novel nano- and microcrystalline high-quality diamonds with luminescent Ge-related centers. Observation of the four-line fine structure in luminescence at 2 eV (602 nm) at temperatures below 80 K manifests a ... More
Scaling relations of supersonic turbulence in star-forming molecular cloudsNov 19 2001We present a direct numerical and analytical study of driven supersonic MHD turbulence that is believed to govern the dynamics of star-forming molecular clouds. We describe statistical properties of the turbulence by measuring the velocity difference ... More
Influence of tearing instability on magnetohydrodynamic turbulenceApr 08 2018Sep 24 2018It has been proposed recently by Loureiro & Boldyrev [Phys. Rev. Lett. 118, 245101 (2017)] and Mallet et al. [Mon. Not. R. Astron. Soc. 468, 4862 (2017)] that strongly anisotropic current sheets formed in the inertial range of magnetohydrodynamic turbulence ... More
Residual energy in magnetohydrodynamic turbulence and in the solar windAug 30 2011Recent observations indicate that kinetic and magnetic energies are not in equipartition in the solar wind turbulence. Rather, magnetic fluctuations are more energetic and have somewhat steeper energy spectrum compared to the velocity fluctuations. This ... More
Numerical Measurements of the Spectrum in Magnetohydrodynamic TurbulenceJun 13 2007We report the results of an extensive set of direct numerical simulations of forced, incompressible, magnetohydrodynamic turbulence with a strong guide field. The aim is to resolve the controversy regarding the power law exponent (\alpha, say) of the ... More
Scalings of intermittent structures in magnetohydrodynamic turbulenceFeb 17 2016Turbulence is ubiquitous in plasmas, leading to rich dynamics characterized by irregularity, irreversibility, energy fluctuations across many scales, and energy transfer across many scales. Another fundamental and generic feature of turbulence, although ... More
Temporal Analysis of Dissipative Structures in Magnetohydrodynamic TurbulenceJun 28 2015Energy dissipation is highly intermittent in turbulent plasmas, being localized in coherent structures such as current sheets. The statistical analysis of spatial dissipative structures is an effective approach to studying turbulence. In this paper, we ... More
Residual Energy in Weak and Strong MHD TurbulenceFeb 15 2012Recent numerical and observational studies revealed that spectra of magnetic and velocity fluctuations in MHD turbulence have different scaling indexes. This intriguing feature has been recently explained in the case of weak MHD turbulence, that is, turbulence ... More
Analog of Astrophysical Magnetorotational Instability in a Couette-Taylor Flow of Polymer FluidsOct 28 2008We report experimental observation of an instability in a Couette-Taylor flow of a polymer fluid in a thin gap between two coaxially rotating cylinders in a regime where their angular velocity decreases with the radius while the specific angular momentum ... More
Temporal Intermittency of Energy Dissipation in Magnetohydrodynamic TurbulenceJan 07 2015Energy dissipation in magnetohydrodynamic (MHD) turbulence is known to be highly intermittent in space, being concentrated in sheet-like coherent structures. Much less is known about intermittency in time, another fundamental aspect of turbulence which ... More
Distribution of Magnetic Discontinuities in the Solar Wind and in MHD TurbulenceOct 12 2012The statistical properties of magnetic discontinuities in the solar wind are investigated by measuring fluctuations in the magnetic field direction, given by the rotation Delta theta that the magnetic field vector undergoes during time interval Delta ... More
Electron Strahl and Halo Formation in the Solar WindNov 02 2018We propose a kinetic model describing the formation of the strahl and halo electron populations in the solar wind. We demonstrate that the suprathermal electrons propagating from the sun along the Parker-spiral magnetic field lines are progressively focused ... More
On the Nature of Magnetic Turbulence in Rotating, Shearing FlowsDec 11 2015The local properties of turbulence driven by the magnetorotational instability (MRI) in rotating, shearing flows are studied in the framework of a shearing-box model. Based on numerical simulations, we propose that the MRI-driven turbulence comprises ... More
Residual Energy in Magnetohydrodynamic TurbulenceJun 11 2011Aug 29 2011There is mounting evidence in solar wind observations and in numerical simulations that kinetic and magnetic energies are not in equipartition in magnetohydrodynamic turbulence. The origin of their mismatch, the residual energy E_r=E_v-E_b, is not well ... More
Dynamic Alignment in Driven Magnetohydrodynamic TurbulenceFeb 17 2006Dec 21 2006Motivated by recent analytic predictions, we report numerical evidence showing that in driven incompressible magnetohydrodynamic turbulence the magnetic- and velocity-field fluctuations locally tend to align the directions of their polarizations. This ... More
Dynamic Alignment and Exact Scaling Laws in MHD TurbulenceMay 09 2006Jun 16 2009Magnetohydrodynamic (MHD) turbulence is pervasive in astrophysical systems. Recent high-resolution numerical simulations suggest that the energy spectrum of strong incompressible MHD turbulence is $E(k_{\perp})\propto k_{\perp}^{-3/2}$. So far, there ... More
Supersonic turbulence and structure of interstellar molecular cloudsMar 25 2002The interstellar medium (ISM) provides a unique laboratory for highly supersonic, driven hydrodynamics turbulence. We present a theory of such turbulence, confirm it by numerical simulations, and use the results to explain observational properties of ... More
Magnetic-field generation in helical turbulenceApr 27 2005Dec 14 2005We investigate analytically the amplification of a weak magnetic field in a homogeneous and isotropic turbulent flow lacking reflectional symmetry (helical turbulence). We propose that the spectral distributions of magnetic energy and magnetic helicity ... More
Extreme Plasma AstrophysicsMar 13 2019This is a science white paper submitted to the Astro-2020 and Plasma-2020 Decadal Surveys. The paper describes the present status and emerging opportunities in Extreme Plasma Astrophysics -- a study of astrophysically-relevant plasma processes taking ... More
Universal small-scale structure in turbulence driven by magnetorotational instabilityFeb 09 2017The intermittent small-scale structure of turbulence governs energy dissipation in many astrophysical plasmas and is often believed to have universal properties for sufficiently large systems. In this work, we argue that small-scale turbulence in accretion ... More
The statistics of a passive scalar in field-guided magnetohydrodynamic turbulenceSep 25 2014A variety of studies of magnetised plasma turbulence invoke theories for the advection of a passive scalar by turbulent fluctuations. Examples include modelling the electron density fluctuations in the interstellar medium, understanding the chemical composition ... More
Intermittency of Energy Dissipation in Alfvenic TurbulenceDec 23 2015We investigate the intermittency of energy dissipation in Alfvenic turbulence by considering the statistics of the coarse-grained energy dissipation rate, using direct measurements from numerical simulations of magnetohydrodynamic turbulence and surrogate ... More
Energy Dissipation in Magnetohydrodynamic Turbulence: Coherent Structures or "Nanoflares"?Sep 11 2014We investigate the intermittency of energy dissipation in magnetohydrodynamic (MHD) turbulence by identifying dissipative structures and measuring their characteristic scales. We find that the probability distribution of energy dissipation rates exhibits ... More
On the energy spectrum of strong magnetohydrodynamic turbulenceSep 10 2012The energy spectrum of magnetohydrodynamic turbulence attracts interest due to its fundamental importance and its relevance for interpreting astrophysical data. Here we present measurements of the energy spectra from a series of high-resolution direct ... More
Magnetic dynamo action in random flows with zero and finite correlation timesJan 26 2011Mar 07 2011Hydromagnetic dynamo theory provides the prevailing theoretical description for the origin of magnetic fields in the universe. Here we consider the problem of kinematic, small-scale dynamo action driven by a random, incompressible, non-helical, homogeneous ... More
Structure Function Scaling in the Taurus and Perseus Molecular Cloud ComplexesJul 25 2002We compute the structure function scaling of the integrated intensity images of two J=1-0 13CO maps of Taurus and Perseus. The scaling exponents of the structure functions follow the velocity scaling of supersonic turbulence, suggesting that turbulence ... More
Stability Analysis of Core-Strahl Electron Distributions in the Solar WindMay 11 2018Jul 08 2018In this work, we analyze the kinetic stability of a solar wind electron distribution composed of core and strahl subpopulations. The core is modeled by a drifting Maxwellian distribution, while the strahl is modeled by an analytic function recently derived ... More
Spectral breaks of Alfvenic turbulence in a collisionless plasmaJul 02 2015Recent observations reveal that magnetic turbulence in the nearly colisionless solar wind plasma extends to scales smaller than the plasma microscales, such as ion gyroradius and ion inertial length. Measured breaks in the spectra of magnetic and density ... More
Numerical simulations of strong incompressible magnetohydrodynamic turbulenceFeb 15 2012Magnetised plasma turbulence pervades the universe and is likely to play an important role in a variety of astrophysical settings. Magnetohydrodynamics (MHD) provides the simplest theoretical framework in which phenomenological models for the turbulent ... More
Structure Function Scaling in Compressible Super-Alfvenic MHD TurbulenceJan 03 2003May 31 2004Supersonic turbulent flows of magnetized gas are believed to play an important role in the dynamics of star-forming clouds in galaxies. Understanding statistical properties of such flows is crucial for developing a theory of star formation. In this letter ... More
Extended Scaling Laws in Numerical Simulations of MHD TurbulenceApr 07 2011Magnetised turbulence is ubiquitous in astrophysical systems, where it notoriously spans a broad range of spatial scales. Phenomenological theories of MHD turbulence describe the self-similar dynamics of turbulent fluctuations in the inertial range of ... More
A reaction network approach to the theory of acoustic wave turbulenceJan 10 2019We propose a new approach to study the long time dynamics of the wave kinetic equation in the statistical description of acoustic turbulence. The approach is based on rewriting the discrete version of the wave kinetic equation in the form of a chemical ... More
Statistical Analysis of Current Sheets in Three-Dimensional Magnetohydrodynamic TurbulenceFeb 06 2013We develop a framework for studying the statistical properties of current sheets in numerical simulations of 3D magnetohydrodynamic (MHD) turbulence. We describe an algorithm that identifies current sheets in a simulation snapshot and then determines ... More
Magnetic Discontinuities in Magnetohydrodynamic Turbulence and in the Solar WindApr 19 2012Recent measurements of solar wind turbulence report the presence of intermittent, exponentially distributed angular discontinuities in the magnetic field. In this Letter, we study whether such discontinuities can be produced by magnetohydrodynamic (MHD) ... More
Test beam studies of the TRD prototype filled with different gas mixtures based on Xe, Kr, and ArDec 08 2016Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a ... More
Splitting of a nondegenerate phonon mode in PrFe3(BO3)4: 4f crystal-field level between TO and LO phonon frequenciesFeb 03 2014A new effect originating from the crystal-field-excitation - phonon coupling was observed (in the far infrared spectra of a multiferroic PrFe3(BO3)4). The reststrahlen band corresponding to the A2 symmetry nondegenerate phonon mode near 50 cm-1 (1.5 THz) ... More
[Plasma 2020 Decadal] Disentangling the Spatiotemporal Structure of Turbulence Using Multi-Spacecraft DataMar 13 2019This white paper submitted for 2020 Decadal Assessment of Plasma Science concerns the importance of multi-spacecraft missions to address fundamental questions concerning plasma turbulence. Plasma turbulence is ubiquitous in the universe, and it is responsible ... More
Kinetic Theory and Fast Wind Observations of the Electron StrahlJun 12 2017Sep 30 2017We develop a model for the strahl population in the solar wind -- a narrow, low-density and high-energy electron beam centered on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances ... More
Inertial Kinetic-Alfvén TurbulenceOct 29 2018Recent observational and analytical studies suggested that a new regime of kinetic turbulence may exist in plasma environments with low electron beta (Chen and Boldyrev, 2017). Such a regime, termed inertial kinetic-Alfv\'en turbulence, is relevant for ... More
Antiferromagnetic dichroism and Davydov splitting of 3d-excitons in a complex multisublattice magnetoelectric CuB2O4Oct 31 2014The space and time symmetry breaking at magnetic phase transitions in multiferroics results in a number of strongly pronounced optical effects. Our high-resolution spectroscopic study of 3d- excitons in a complex multi-sublattice magnetoelectric CuB2O4 ... More
Antiferromagnetic Stabilization in Ti8O12Dec 08 2015Using the evolutionary algorithm USPEX and DFT+U calculations, we predicted a high-symmetry geometric structure of bare Ti8O12 cluster composed of 8 Ti atoms forming a cube, which O atoms are at midpoints of all of its edges, in excellent agreement with ... More
Spectral scaling laws in MHD turbulence simulations and in the solar windJun 03 2011The question is addressed to what extent incompressible magnetohydrodynamics (MHD) can describe random magnetic and velocity fluctuations measured in the solar wind. It is demonstrated that distributions of spectral indices for the velocity, magnetic ... More
Dirac cones in Two-dimensional BoraneNov 27 2017We introduce two-dimensional borane, a single-layered material of BH stoichiometry, with promising electronic properties. We show that, according to Density Functional Theory calculations, two-dimensional borane is semimetallic, with two symmetry-related ... More
Spectroscopy of f-f transitions, crystal-field calculations, and magnetic and quadrupole helix chirality in DyFe$_3$(BO$_3$)$_4$Nov 21 2016Nov 23 2016Recently, quadrupole helix chirality and its domain structure was observed in resonant x-ray diffraction experiments on DyFe$_3$(BO$_3$)$_4$ using circularly polarized x rays [T. Usui et al., Nature Materials 13, 611 (2014)]. We show that this effect ... More
Two-Dimensional Magnetic BoronDec 17 2015We predict a two-dimensional (2D) antiferromagnetic (AFM) boron (designated as M-boron) by using ab initio evolutionary methodology. M-boron is entirely composed of B20 clusters in a hexagonal arrangement. Most strikingly, the highest valence band of ... More
Spectroscopy of f-f transitions, crystal-field calculations, and magnetic and quadrupole helix chirality in DyFe$_3$(BO$_3$)$_4$Nov 21 2016Recently, quadrupole helix chirality and its domain structure was observed in resonant x-ray diffraction experiments on DyFe3(BO3)4 using circularly polarized x rays [T. Usui et al., Nature Materials 13, 611 (2014)]. We show that this effect can be explained ... More
Bifurcations observed in the spectra of coupled electron-phonon modes in multiferroic $PrFe_3(BO_3)_4$ subjected to a magnetic fieldSep 07 2016We report on bifurcations effect mediated by the electron-phonon coupling in a concentrated rare-earth-containing antiferromagnet, observed in the spectra of coupled $4f$-electron-phonon modes under the influence of an external magnetic field. The effect ... More
Bulk graphanes synthesized from benzene and pyridineAug 25 2016We report a high-pressure high-temperature synthesis of several millimeter-sized samples of bulk graphanes with the composition C-H(D) from benzene and graphene-derivative C-H-N$_{0.2}$ from pyridine. X-ray diffraction, transmission electron microscopy, ... More
Lattice dynamics and electronic transitions in a structurally-complex layered copper borate Cu$_3$(BO$_3$)$_2$Oct 09 2017Nov 27 2017Copper borate Cu$_3$(BO$_3$)$_2$ is a complex compound with a layered crystallographic structure in which the Jahn-Teller active and magnetic copper Cu$^{2+}$ ions occupy sixteen nonequivalent positions in the unit cell displaying controversial magnetic ... More
Lattice dynamics and a magnetic-structural phase transition in the nickel orthoborate $Ni_{3}(BO_{3})_{2}$Sep 01 2015Jan 27 2016Nickel orthoborate $Ni_{3}(BO_{3})_{2}$ having a complex orthorhombic structure $P_{nnm}$ (#58, Z=2) of the kotoite type is known for quite a long time as an antiferromagnetic material below $T_{N}$ = 46 K, but up to now its physical properties including ... More
Band insulator to Mott insulator transition in a bilayer Hubbard modelMar 27 2007The ground state phase diagram of the half-filled repulsive Hubbard model in a bilayer is investigated using cluster dynamical mean field theory. For weak to intermediate values of Coulomb repulsion $U$, the system undergoes a transition from a Mott insulating ... More
NNLO classical solution for Lipatov's effective action for reggeized gluonsFeb 15 2018Mar 19 2018We consider the formalism of small-x effective action for reggeized gluons, Gribov (Sov Phys JETP 26:414, 1968), Lipatov (Nucl Phys B 452:369, 1995; Phys Rep 286:131, 1997; Subnucl Ser 49:131, 2013, Int J Mod Phys Conf Ser 39:1560082, 2015; Int J Mod ... More
A stable compound of helium and sodium at high pressureSep 16 2013Feb 14 2017Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, ... More
Modelling the VHE flare of 3C 279 using one zone leptonic modelSep 12 2011We model the simultaneous observations of the flat spectrum radio quasar 3C 279 at radio, optical, X-ray and very high energy (VHE) gamma ray energies during 2006 flare using a simple one zone leptonic model. We consider synchrotron emission due to cooling ... More