Suppression of magnetotransport in strongly disordered graphene

A tight-binding model with randomly fluctuating atomic positions is studied to discuss the effect of strong disorder in graphene. We employ a strong-disorder expansion for the transport quantities and find a diffusive behavior, where the conductivity is decreasing with increasing disorder. For sufficiently strong disorder the magnetic field drops out of the diffusion coefficient and the conductivity. This signals a strong suppression of magnetotransport effects, a result which is consistent with recent experimental observations by Morozov et al.     

Intrinsic spin Hall edges

The prediction of intrinsic spin Hall currents by Murakami et al. and Sinova et al. raised many questions about methods of detection and the effect of disorder. We focus on a contact between a Rashba-type spin-orbit coupled region with a normal two-dimensional electron gas and show that the spin Hall currents, though vanishing in the bulk of the sample, can be recovered from the edges. We also show that the current-induced spin accumulation in the spin-orbit coupled system diffuses into the normal region and contributes to the spin current in the leads.     

Colossal dielectric constant in high entropy oxides

Entropic contributions to the stability of solids are very well understood and the mixing entropy has been used for forming various solids, for instance such as inverse spinels, see Nawrotsky et al., J. Inorg. Nucl. Chem. 29 , 2701 (1967) [1]. A particular development was related to high entropy alloys by Yeh et al., Adv. Eng. Mater. 6 , 299 (2004) [2] and Cantor et al., Mater. Sci. Eng. A 375–377 , 213 (2004) [3] (for recent reviews see Zhang et al., Prog. Mater. Sci. 61 , 1 (2014) [4] and Tsai et al., Mater. Res. Lett. 2 , 107 (2014) [5]) in which the configurational disorder is responsible for forming simple solid solutions and which are thoroughly studied for various applications especially due to their mechanical properties, e.g. Gludovatz et al., Science 345 , 1153 (2014) [6] and Lu et al., Sci. Rep. 4 , 6200 (2014) [7], but also electrical properties, Kozelj et al., Phys. Rev. Lett. 113 , 107001 (2014) [8], hydrogen storage, Kao et al., Int. J. Hydrogen Energy 35 , 9046 (2010) [9], magnetic properties, Zhang et al., Sci. Rep. 3 , 1455 (2013) [10]. Many unexplored compositions and properties still remain for this class of materials due to their large phase space. In a recent report it has been shown that the configurational disorder can be used for stabilizing simple solid solutions of oxides, which should normally not form solid solutions, see Rost et al., Nature Commun. 6 , 8485 (2015) [11] these new materials were called ”entropy‐stabilized oxides”. In this pioneering report, it was shown that mixing five equimolar binary oxides yielded, after heating at high temperature and quenching, an unexpected rock salt structure compound with statistical distribution of the cations in a face centered cubic lattice. Following this seminal study, we show here that these high entropy oxides (named HEOx hereafter) can be substituted by aliovalent elements with a charge compensation mechanism. This possibility largely increases the potential development of new materials by widening their (already complex) phase space. As a first example, we report here that at least one HEOx composition exhibits colossal dielectric constants, which could make it very promising for applications as large‐k dielectric materials. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Interplay between elastic fields due to gravity and a partial dislocation for a hard-sphere crystal coherently grown under gravity: driving force for defect disappearance

We previously observed that an intrinsic staking fault shrunk through a glide of a Shockley partial dislocation terminating its lower end in a hard-sphere crystal under gravity coherently grown in ?001? by Monte Carlo simulations [Mori et al., Molec. Phys. 105, 1377 (2007)]; it was an answer to a one-decade long standing question why the stacking disorder in colloidal crystals reduced under gravity [Zhu et al., Nature 387, 883 (1997)]. Here, we present an elastic energy calculation; in addition to the self-energy of the partial dislocation [Mori et al., Prog. Theor. Phys. Suppl. 178, 33 (2009)] we calculate the cross-coupling term between elastic field due to gravity and that due to a Shockley partial dislocation. The cross-term is an increasing function of the linear dimension R over which the elastic field expands, showing that a driving force arises for the partial dislocation moving toward the upper boundary of a grain.     

Nonsteady condensation and evaporation waves

Recent scaling results for the ac conductivity of ionic glasses by Roling et al. [Phys. Rev. Lett. 78, 2160 (1997)] and Sidebottom [Phys. Rev. Lett. 82, 3653 (1999)] are discussed. We prove that Sidebottom's version of scaling is completely general. A new approximation to the universal ac conductivity arising in the extreme disorder limit of the symmetric hopping model, the "diffusion cluster approximation," is presented and compared to computer simulations and experiments.     

Infinite randomness fixed point of the superconductor-metal quantum phase transition

We examine the influence of quenched disorder on the superconductor-metal transition, as described by a theory of overdamped Cooper pairs which repel each other. The self-consistent pairing eigenmodes of a quasi-one-dimensional wire are determined numerically. Our results support the recent proposal by Hoyos et al. [Phys. Rev. Lett. 99, 230601 (2007)10.1103/PhysRevLett.99.230601] that the transition is characterized by the same strong-disorder fixed point describing the onset of ferromagnetism in the random quantum Ising chain in a transverse field.     

Projected spin functions for many electron systems

The krypton potentials of Barker et al., Buck et al., Gough et al. (Maitland and Smith (n-6)) and Thakkar and Smith (MIST 2C and 6B) are compared as to their ability to predict dilute gas properties (second virial, viscosity, self-diffusion and thermal conductivity coefficients and thermal diffusion factors). The potentials of Barker et al. and Buck et al. and Gough et al. (MS) accurately predict these properties almost equally. The MIST potentials do not fare quite so well. The isotopic thermal diffusion factor, the dilute gas property most sensitive to the shape of the potential, is best described by the Buck et al. and MS potentials. An analysis of this property suggests the correctness of the slope of the repulsive wall of these potentials.     

Improving the Reversible LSB Matching Scheme Based on the Likelihood Re-Encoding Strategy

In 2018, Tseng et al. proposed a dual-image reversible embedding method based on the modified Least Significant Bit matching (LSB matching) method. This method improved on the dual-image LSB matching method proposed by Lu et al. In Lu et al.’s scheme, there are seven situations that cannot be restored and need to be modified. Furthermore, the scheme uses two pixels to conceal four secret bits. The maximum modification of each pixel, in Lu et al.’s scheme, is two. To decrease the modification, Tseng et al. use one pixel to embed two secret bits and allow the maximum modification to decrease from two to one such that the image quality can be improved. This study enhances Tseng et al.’s method by re-encoding the modified rule table based on the probability of each hiding combination. The scheme analyzes the frequency occurrence of each combination and sets the lowest modified codes to the highest frequency case to significantly reduce the amount of modification. Experimental results show that better image quality is obtained using our method under the same amount of hiding payload.     

Sea Level Muon Spectrum Derived from Bugaev Model Using the Primary Cosmic Ray Energy Spectrum of Grigorov et al

In a recent paper BHATTACHARYYA has derived the pion and kaon production spectra in the atmosphere using a form of the primary nucleon energy spectrum of the measurements of GRIGOROV et al. and the interaction model of BUGAEV et al. The sea level muon spectrum derived from these meson spectra agrees with the magnetic spectrograph data of ALLKOFER et al. and AYRE et al. In this report a critical analysis of the paper has been made and some obvious mistakes in the formulation have been pointed out. The formulation of BUGAEV et al. and the data of GRIGOROV at al. have been misinterpreted by BHATTACHARYYA . The corrected results have been properly interpreted in this report.     

Rotating superfluid turbulence

Almost all studies of vortex states in helium II have been concerned with either ordered vortex arrays or disordered vortex tangles. This work numerically studies what happens in the presence of both rotation (which induces order) and thermal counterflow (which induces disorder). We find a new statistically steady state in which the vortex tangle is polarized along the rotational axis. Our results are used to interpret an instability that was discovered experimentally by Swanson et al. [Phys. Rev. Lett. 50, 190 (1983)]] and the vortex state beyond the instability that has been unexplained until now.     

Frequency spectrum of Cherenkov radiation and radioastronomical method for measuring the flux of ultrahigh-energy cosmic particles

The frequency spectrum of a radio pulse generated by a cascade shower in the Moon’s regolith has been calculated with the inclusion of the transverse sizes of the shower and the inhomogeneous distribution of excess electrons over the disc radius. The character of the spectrum differs significantly from the previous results that were obtained by E. Zas et al., Phys. Rev. D 45, 362 (1992), and J. Alvarez-Muñis et al., astro-ph/0003315, and were more recently used by T. H. Hankins et al., Mon. Not. R. Astron. Soc. 283, 1027 (1996); P. W. Gorham et al., astro-ph/9906504; and P. W. Gorham et al., astro-ph/0310232. The maximum-intensity region lies in a range of 500–600 MHz. In a frequency range of 1.5–2 GHz, the radiation intensity decreases by several orders of magnitude. This seems to be one of the causes of the absence of events in experimental works of T. H. Hankins et al., Mon. Not. R. Astron. Soc. 283, 1027 (1996); P. W. Gorham et al., astro-ph/9906504; and P. W. Gorham et al., astro-ph/0310232, which closed Z-burst models.     

Matrix-continued fraction solutions of some stochastic equations with random telegraph noise

The seven independent adiabatic elastic constants of CaWO₄ are calculated using Born's longwave method and the rigid ion model of Steinman et al. (1972). Good agreement exists between the calculated elastic constants and those measured by Gluyas et al. (1973). The sign of C₁₆ is consistent with the observation of Farley et al. (1972). Further the dynamical equilibrium conditions are also found to be satisfied for this model.     

Dependence of single-bubble sonoluminescence on ambient pressure

Kondic et al.'s theory makes several specific predictions on the dependence of single-bubble sonoluminescence (SBSL) on ambient pressure. We have carried out experiments to verify these predictions for air bubbles in a water-glycerine mixture at about 17.5 kHz. The results show an increase in SBSL with reduced ambient pressure down to a critical value below which SBSL is extinguished. The results are all in good agreement with Kondic et al.'s theory and are also compatible with the dissociation hypothesis of Lohse et al.     

Strong coupling regime in semiconductor microcavities

We introduce to the physics of semiconductor microcavities in the strong coupling regime, also known as cavity-polariton. We discuss the optical response, cavity-polariton dispersion curve, inhomogeneous broadening due to disorder effect and homogeneous broadening due to acoustic phonon scattering. We present novel effects on high quality samples on elastic scattering and parametric oscillation effects in the non-linear response under resonant excitation. To cite this article: R. Houdré et al., C. R. Physique 3 (2002) 15–27     

Unified model of deep inelastic heavy ion collisions: Collectivity and statistics

Deep inelastic heavy ion collisions are viewed as multi-step processes described in terms of coupled-channel equations. Including both statistical and collective excitations, it is shown that in the semi-classical limit the coupled-channel equations reduce to a classical equation of motion for the relative coordinate with frictional force, master equation for the intrinsic occupation probabilities, and a damped forced harmonic oscillation for the mean deformation of the ions. We therefore succeed in unifying the approaches of Agassi et al. and Broglia et al., and in justifying the phenomenological models of Deubler et al. and Abul-Magd et al.     

Auger kinetic energies and electronic relaxation phenomena in atoms and solids

A semi-empirical theory has been developed to calculate the kinetic energy of Auger electrons resulting from radiationless transitions in both free atoms and metals. Experimental electron binding energies and calculated two-electron interaction and relaxation energies are used. Relaxation energies are determined by means of hyper-Hartree—Fock hole-state calculations. To account for extra-atomic relaxation phenomena in metals, it is assumed that conductionband electrons occupy free-atom-like screening orbitais. The relationship of the present theory to recent work of Shirley et al., Larkins, Kim et al. and Watson et al. is discussed. The dependence of the Auger cross-relaxation energy on the ionicity of compounds is briefly discussed.     

Derivation of Absolute Depth-Intensity Spectrum under Standard Rock from the Recently Estimated Primary Cosmic Ray Spectrum

Using the recently derived primary cosmic ray nucleon spectrum from JACEE and GSFC balloon flight data and Fermilab results for pp → π^± + X anything inclusive reaction data in the light of Feynman scaling the depth-intensity spectrum under standard rock has been estimated. A precisely constructed range-energy relation has been applied in this analysis. The derived spectrum when corrected for range fluctuation agrees approximately with the experimental data under standard rocks measured by MIYAZAKI , BARTON , CASTAGNOLI et al., MEYER et al., BERGAMASCO et al., SHELDON et al. and BASCHIERA et al.     

Yb∶KGW激光晶体无热方向的计算与分析

针对各向异性Yb∶KGW激光晶体有可能存在热透镜效应为零的传播方向（即无热方向）,利用Biswal等人2篇文献和Pujol等人对Yb∶KGW晶体热膨胀系数的测量结果,分别采用最小二乘法和二阶张量旋转计算出对应晶体的热膨胀张量,据此计算出2篇文献中所述晶体的无热方向。通过对比分析发现：尽管晶体热膨胀张量存在一定的个体差异,但是该晶体普遍只存在2个无热方向,即当光为m偏振时,在p-g平面内与p轴成正负二十多度的2个方向,而不是Biswal等人给出的4个无热方向。另外,利用得到的热膨胀张量计算出某特定方向的热光特性与瑞典的Hellstrom等人报道的激光器热透镜实验结果相一致。     

The conductivity of a two-dimensional electronic system of finite width in the presence of a strong perpendicular magnetic field and a random potential

Starting from the Kubo formula the conductivity tensor of a two-dimensional electronic system in a perpendicular magnetic field is evaluated. It is shown that at zero temperature only the states at the Fermi level contribute. The Hall conductivity of a purely periodic system of finite width is calculated and compared with earlier suggestions by Thouless et al. For a system described by a periodic and a random potential the Hall conductivity is calculated as a function of the electron density. The results emphasize the importance of disorder independent current carrying states for the Quantum Hall effect which extend along the boundaries of the system. The plateaux values of the Hall conductivity are related to the number of these states, and are independent of the existence of extended bulk states below the Fermi energy.     

Chromatin physics: Replacing multiple, representation-centered descriptions at discrete scales by a continuous, function-dependent self-scaled model

This commentary on the inspiring works and ideas by Langowski, Mangeol et al., Lee et al., Bundschuh and Gerland, Schiessel, Vaillant et al., Lesne and Victor, Claudet and Bednar, Fuks, Allemand et al., and Blossey, all appearing in this issue (Eur. Phys. J. E 19 (2006)), expresses our felt need of novel approaches to chromatin modeling.