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Driven by the Beam Energy Scan (BES) program at the RHIC, researches and discussions on the QCD phase diagram have flourished recently. In order to provide a reference from microscopic transport models, we performed a systematic analysis, using a multiphase transport (AMPT) model for the particle yields and a statistical model (THERMUS) for the thermal fit, for Au + Au collisions at √sNN=7.7-200 GeV. It is found that at a fixed collision centrality the chemical freeze-out parameter, temperature Tch, increases with collision energy and somehow saturates at certain values of Tch in collisions near √sNN=10 GeV, indicating the limiting temperature in hadronic interactions; meanwhile the baryon chemical potential μB decrease with the collision energy. The saturation temperature is also found to be dependent on partonic interaction. At a given collision energy, it is found that both Tch and μB decrease towards more peripheral collisions in the grand canonical approach. The energy and centrality dependence of other chemical freeze-out parameters, strangeness chemical potential μS, strangeness undersaturation factor γS, and the volume of the fireball V are also presented in this paper. The chemical potential ratio μs/μB is also compared with lattice QCD calculation. The AMPT default model gives better descriptions on both the particle yields and the chemical freeze-out parameters than those from the AMPT string-melting model. [ABSTRACT FROM AUTHOR]

Using cluster perturbation theory, we explain the origin of the strongly dispersive feature found at high binding energy in the spectral function of the Hubbard model. By comparing the Hubbard and t-J-3s model spectra, we show that this dispersion does not originate from either coupling to spin fluctuations (αJ ) or the free hopping (αt ). Instead, it should be attributed to a long-range, correlated hopping αt2/U, which allows an effectively free motion of the hole within the same antiferromagnetic sublattice. This origin explains both the formation of the high-energy anomaly in the single-particle spectrum and the sensitivity of the high-binding-energy dispersion to the next-nearest-neighbor hopping t'. [ABSTRACT FROM AUTHOR]

The ablator couples energy between the driver and fusion fuel in inertial confinement fusion (ICF). Because of its low opacity, high solid density, and material properties, beryllium has long been considered an ideal ablator for ICF ignition experiments at the National Ignition Facility. We report here the first indirect drive Be implosions driven with shaped laser pulses and diagnosed with fusion yield at the OMEGA laser. The results show good performance with an average DD neutron yield of ~2 x 109 at a convergence ratio of R0/R ~ 10 and little impact due to the growth of hydrodynamic instabilities and mix. In addition, the effect of adding an inner liner of W between the Be and DD is demonstrated. [ABSTRACT FROM AUTHOR]

Superconducting Sr3Rh4Sn13 has been of current interest due to indications of a characteristic phase transition associated with structural distortions in its normal state. Tofurther shed light on the nature of the phase transition, we performed a detailed study of single crystalline Sr3Rh4Sn13 by means of the thermal expansion, electrical resistivity, Hall coefficient, Seebeck coefficient, thermal conductivity, as well as 119Sn nuclear magnetic resonance (NMR) measurements, mainly focusing on the signatures around the phase transition temperature T* = 137 K. The phase transition has been characterized by marked features near T* in all measured physical quantities. In particular, the NMR characteristics provide microscopic evidence for the reduction in the electronic Fermi-level density of states (DOSs) below T*. Based on the analysis of the 119Sn NMR spin-lattice relaxation rate, we clearly demonstrated that the Sn 5s partial Fermi-level DOS in Sr3Rh4Sn13 is reduced by 13% across the phase transition. In this respect, it points to the strong association between electronic and structural instability for the peculiar phase transition in Sr3Rh4Sn13. [ABSTRACT FROM AUTHOR]

The total spectral weight S of the emergent low-energy quasiparticles in high-temperature superconductors (HTSCs) is explored by x-ray absorption spectroscopy. In order to examine the applicability of the Hubbard model, regimes that cover from zero doping to overdoping are investigated. In contrast to results of mean-field theory, we found that S deviates from linear dependence on the doping level p. The slope of S versus p changes continuously throughout the whole doping range with no sign of saturation up to p=0.23. Therefore, the picture of the Zhang-Rice singlet remains intact within the most prominent doping regimes of HTSCs. [ABSTRACT FROM AUTHOR]

We report that the finite thickness of three-dimensional topological insulator (TI) thin films produces an observable magnetoresistance (MR) in phase coherent transport in parallel magnetic fields. The MR data of Bi2 Se3 and (Bi1-xSbx)2Te3 thin films are compared with existing theoretical models of parallel field magnetotransport. We conclude that the TI thin films bring parallel field transport into a unique regime in which the coupling of surface states to bulk and to opposite surfaces is indispensable for understanding the observed MR. The β parameter extracted from parallel field MR can in principle provide a figure of merit for searching TI compounds with more insulating bulk than existing materials. [ABSTRACT FROM AUTHOR]

An intrinsic thermoelectric coupling effect in the linear response regime of magnetic tunneling junctions (MTJ) is reported. In the dc response, it leads to a nonlinear correction to Ohm's law. Dynamically, it enables a novel Seebeck rectification and second harmonic generation, which apply for a broad frequency range and can be magnetically controlled. A phenomenological model on the footing of the Onsager reciprocal relation and the principle of energy conservation explains very well the experimental results obtained from both dc and frequency-dependent transport measurements performed up to GHz frequencies. Our work refines previous understanding of magnetotransport and microwave rectification in MTJs. It forms a new foundation for utilizing spin caloritronics in high-frequency applications. [ABSTRACT FROM AUTHOR]

Quasiparticle dynamics of FeSe single crystals revealed by dual-color transient reflectivity measurements (&Dgr;R/R) provides unprecedented information on Fe-based superconductors. The amplitude of the fast component in AR/R clearly gives a competing scenario between spin fluctuations and superconductivity. Together with the transport measurements, the relaxation time analysis further exhibits anomalous changes at 90 and 230 K. The former manifests a structure phase transition as well as the associated phonon softening. The latter suggests a previously overlooked phase transition or crossover in FeSe. The electron-phonon coupling constant A is found to be 0.16, identical to the value of theoretical calculations. Such a small A demonstrates an unconventional origin of superconductivity in FeSe. [ABSTRACT FROM AUTHOR]

A equation of state (EOS) experimental technique that enables the study of thermodynamic derivatives into the TPa regime is described and applied to boron carbide (B4C). Data presented here are principal Hugoniot sound speed measurements reported using a laser-driven shock platform, providing a means to explore the high-pressure off-Hugoniot response of opaque materials. The extended B4C Hugoniot suggests the presence of a high-pressure phase, as recently predicted by molecular dynamics simulations, adding to the complexity of the existing phase diagram. [ABSTRACT FROM AUTHOR]

Structural phase transitions in Sr3Rh4Sn13 and Sr3Ir4Sn13 are currently of interest due to the evidence of strong correlation with their superconductivity. To further obtain additional insight into the thermodynamic properties of the phase transitions, we have performed a study of single-crystalline Sr3Rh4Sn13 and Sr3Ir4Sn13 by means of the specific-heat and thermal-expansion measurements, mainly focusing on the features around the phase-transition temperature T*≃138 and 147 K, respectively. In particular, the specific-heat data have been analyzed in the framework of the critical fluctuation model in addition to a mean-field contribution. Relatively large critical exponents were obtained for Sr3Ir4Sn13, suggesting a shorter coherence length associated with the phase transition. For each compound, an enhancement in the mean-field jump compared to the BCS value has been quantitatively identified, revealing the strong-coupling characteristics for the observed phase transitions. Furthermore, prominent changes in the coefficient of linear thermal expansion and bulk modulus across T* have been identified, providing new information about the structural phase transitions in the title compounds. [ABSTRACT FROM AUTHOR]

Using cluster perturbation theory, we explain the origin of the strongly dispersive feature found at high binding energy in the spectral function of the Hubbard model. By comparing the Hubbard and t-J-3s model spectra, we show that this dispersion does not originate from either coupling to spin fluctuations (∝J) or the free hopping (∝t). Instead, it should be attributed to a long-range, correlated hopping ∝t²/U, which allows an effectively free motion of the hole within the same antiferromagnetic sublattice. This origin explains both the formation of the high-energy anomaly in the single-particle spectrum and the sensitivity of the high-binding-energy dispersion to the next-nearest-neighbor hopping t'. [ABSTRACT FROM AUTHOR]

We studied the defects of Bi2Se3 generated from Bridgman growth of stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size, and transport properties are strongly affected by the types of defects generated. Major defect types of the BiSe antisite and partial Bi2-layer intercalation are identified through combined studies of direct atomic-scale imaging with scanning transmission electron microscopy in conjunction with energy-dispersive x-ray spectroscopy, x-ray diffraction, and Hall effect measurements. We propose a consistent explanation to the origin of defect type, growth morphology, and transport property. [ABSTRACT FROM AUTHOR]