6,835 research outputs found

    Electronic Orders Induced by Kondo Effect in Non-Kramers f-Electron Systems

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    This paper clarifies the microscopic nature of the staggered scalar order, which is specific to even number of f electrons per site. In such systems, crystalline electric field (CEF) can make a singlet ground state. As exchange interaction with conduction electrons increases, the CEF singlet at each site gives way to Kondo singlets. The collective Kondo singlets are identified with itinerant states that form energy bands. Near the boundary of itinerant and localized states, a new type of electronic order appears with staggered Kondo and CEF singlets. We present a phenomenological three-state model that qualitatively reproduces the characteristic phase diagram, which have been obtained numerically with use of the continuous-time quantum Monte Carlo combined with the dynamical mean-field theory. The scalar order observed in PrFe_4P_{12} is ascribed to this staggered order accompanying charge density wave (CDW) of conduction electrons. Accurate photoemission and tunneling spectroscopy should be able to probe sharp peaks below and above the Fermi level in the ordered phase.Comment: 7 pages, 8 figure

    Non-collinear magnetism in Al-Mn topologically disordered systems

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    We have performed the first ab-initio calculations of a possible complex non-collinear magnetic structure in aluminium-rich Al-Mn liquids within the real-space tight-binding LMTO method. In our previous work we predicted the existence of large magnetic moments in Al-Mn liquids [A.M. Bratkovsky, A.V. Smirnov, D. N. Manh, and A. Pasturel, \prb {\bf 52}, 3056 (1995)] which has been very recently confirmed experimentally. Our present calculations show that there is a strong tendency for the moments on Mn to have a non-collinear (random) order retaining their large value of about 3~μB\mu_B. The d-electrons on Mn demonstrate a pronounced non-rigid band behaviour which cannot be reproduced within a simple Stoner picture. The origin of the magnetism in these systems is a topological disorder which drives the moments formation and frustrates their directions in the liquid phase.Comment: 10 pages, RevTex 3.0, 24kb. 3 PS figures available on request from [email protected] The work has been presented at ERC ``Electronic Structire of Solids'' (Lunteren, The Netherlands, 9-14 September 1995

    Elastic Cross Sections for Electron Collisions with Molecules Relevant to Plasma Processing

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    Absolute electron-impact cross sections for molecular targets, including their radicals, are important in developing plasma reactors and testing various plasma processing gases. Low-energy electron collision data for these gases are sparse and only the limited cross section data are available. In this report, elastic cross sections for electron-polyatomic molecule collisions are compiled and reviewed for 17molecules relevant to plasma processing. Elastic cross sections are essential for the absolute scale conversion of inelastic cross sections, as well as for testing computational methods. Data are collected and reviewed for elastic differential, integral, and momentum transfer cross sections and, for each molecule, the recommended values of the cross section are presented. The literature has been surveyed through early 2010.This work is accomplished as a collaboration through APAN (Asia-Pacific Atomic Data Network: a network for dissemination of collisional data relevant to plasmas, discharges, materials, and biosciences). H.C. acknowledges a support by the National Research Foundation of Korea (Grant No. 20100000035), and M.J.B. and S.J.B. support from the Australian Research Council Center of Excellence for Antimatter-Matter Studies. Collaboration between NIFS and NFRI is also acknowledged for the Korea-Japan exchanges

    Relativistic Particle Acceleration in a Folded Current Sheet

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    Two-dimensional particle simulations of a relativistic Harris current sheet of pair plasmashave demonstrated that the system is unstable to the relativistic drift kink instability (RDKI) and that a new kind of acceleration process takes place in the deformed current sheet. This process contributes to the generation of non-thermal particles and contributes to the fast magnetic dissipation in the current sheet structure. The acceleration mechanism and a brief comparison with relativistic magnetic reconnection are presented.Comment: 11 preprint pages, including 3 .eps figure

    Mott insulator in two-channel Kondo lattice

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    The Mott insulator is found in the two-channel Kondo lattice by using the dynamical mean-field theory combined with continuous-time quantum Monte Carlo method. At quarter filling of two conduction bands, the paramagnetic state shows metal-insulator crossover with increasing the coupling constant at low temperatures. The insulating state is explained by the strong coupling limit, where the system is effectively interpreted as the half-filled Hubbard model. It is shown that the present Mott insulating state is well described by the Hubbard I approximation

    Properties of the cosmological filament between two clusters: A possible detection of a large-scale accretion shock by SuzakuSuzaku

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    We report on the results of a SuzakuSuzaku observation of the plasma in the filament located between the two massive clusters of galaxies Abell 399 and Abell 401. Abell 399 (zz=0.0724) and Abell 401 (zz=0.0737) are expected to be in the initial phase of a cluster merger. In the region between the two clusters, we find a clear enhancement in the temperature of the filament plasma from 4 keV (expected value from a typical cluster temperature profile) to kT∼kT\sim6.5 keV. Our analysis also shows that filament plasma is present out to a radial distance of 15' (1.3 Mpc) from a line connecting the two clusters. The temperature profile is characterized by an almost flat radial shape with kT∼kT\sim6-7 keV within 10' or ∼\sim0.8 Mpc. Across rr=8'~from the axis, the temperature of the filament plasma shows a drop from 6.3 keV to 5.1 keV, indicating the presence of a shock front. The Mach number based on the temperature drop is estimated to be M∼{\cal M}\sim1.3. We also successfully determined the abundance profile up to 15' (1.3 Mpc), showing an almost constant value (ZZ=0.3 solar) at the cluster outskirt. We estimated the Compton yy-parameter to be ∼\sim14.5±1.3×10−6\pm1.3\times10^{-6}, which is in agreement with PlanckPlanck's results (14-17×10−6\times10^{-6} on the filament). The line of sight depth of the filament is l∼l\sim1.1 Mpc, indicating that the geometry of filament is likely a pancake shape rather than cylindrical. The total mass of the filamentary structure is ∼\sim7.7×1013 M⊙\times10^{13}~\rm M_{\odot}. We discuss a possible interpretation of the drop of X-ray emission at the rim of the filament, which was pushed out by the merging activity and formed by the accretion flow induced by the gravitational force of the filament.Comment: 8 pages, 8 figures, accepted for publication in A&

    Continuum Scaling from Large Mass Expansion on the Lattice: Delta Expansion Applied to the Anharmonic Oscillator

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    We dilate the scaling region of the lattice anharmonic oscillator at strong coupling by introducing the parameter delta. Performing expansion in delta, the calculation of the mass gap in the continuum limit via the series expansion effective at large lattice spacings is then studied. We show that the dilation on the mass parameter M recovers the scaling behavior of the hopping parameter beta and allows for precise approximation of the mass gap.Comment: 10 page
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