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  • 1
    Electronic Resource
    Electronic Resource
    Effects of electron-hole correlation on ultrasonic attenuation in bismuth in strong magnetic fields (1979)
    Springer
    The European physical journal 35 (1979), S. 233-243 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A theory is developed on giant quantum attenuation of ultrasound in bismuth. The present theory successfully explains the following experimental results in strong magnetic fields (H ≲ 100 kG): (i) When two attenuation peaks, the one due do electrons and the other due to holes, coincide as a function of magnetic field, the attenuation is exceptionally large at temperatures around 1 K and decreases rapidly with increasing temperatures; (ii) on the contrary, an isolated attenuation peak shows only a weak temperature dependence; (iii) the line shape of an isolated hole peak is highly asymmetric. The theory includes both intraband and interband impurity scatterings, acoustic phonon scattering, and takes account of Coulomb correlation effects via electron-electron, hole-hole and electron-hole two-body distribution functions. As a result, the electron-hole attractive correlation is found to play a crucial role in making the large attenuation mentioned in (i). For (ii), the electron-hole correlation is ineffective because of the large difference in Fermi velocities, and the acoustic phonon scattering is found to be important. Finally, the result (iii) is attributed to the small density of states of the reservoir Landau subbands in the strong magnetic field regime. The present theory assumes no phase transition to account for the result (i) in contrast to previous theories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01319843
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamical susceptibilities of intermediate valence compounds (1980)
    Springer
    The European physical journal 37 (1980), S. 299-305 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Relaxation rates of magnetic moment and charge are discussed for systems showing intermediate valence. The periodic Anderson model and a more realistic model with periodic 4f shells are investigated by the use of the Mori formalism. It is shown that the relaxation of the 4f moment and the charge above the “spin fluctuation” temperature is dominated by the second order process with respect to the hybridization interaction and is nearly independent of temperature. The moment relaxation rate is significantly larger than that in the integral valent case where the fourth order Korringa process is dominant. The theory can explain the anomalously large width and the momentum independent nature of the quasi-elastic component of the neutron scattering on intermediate valence compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01352739
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  • 3
    Electronic Resource
    Electronic Resource
    Perturbative renormalization of multi-channel Kondo-type models (1998)
    Springer
    The European physical journal 5 (1998), S. 457-464 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 05.30.-d Quantum statistical mechanics - 05.70.Jk Critical point phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The poor man's scaling is extended to higher order by the use of the open-shell Rayleigh-Schrödinger perturbation theory. A generalized Kondo-type model with the SU(n) SU(m) symmetry is proposed and renormalized to the third order. It is shown that the model has both local Fermi-liquid and non-Fermi-liquid fixed points, and that the latter becomes unstable in the special case of n=m=2. Possible relevance of the model to the newly found phase IV in CexLa1-xB6 is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510050466
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  • 4
    Electronic Resource
    Electronic Resource
    Self-consistent perturbation theory for dynamics of valence fluctuations (1984)
    Springer
    The European physical journal 57 (1984), S. 95-105 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dynamical properties of valence-fluctuating systems are studied at absolute zero of temperature. The self-consistent perturbation theory developed for rare-earth impurity systems is used with some refinement. The theory takes account of the orthogonality catastrophe caused by hybridization of 4f and conduction electrons. Extensive numerical results are reported for the 4f-electron density of states ϱ4f (ɛ) and the dynamical magnetic susceptibility χ(ω). The results cover both the intermediate-valence and nearly integral-valence regimes of a model Ce impurity system. The present theory gives reasonable overall feature of dynamics including a sharp peak in ϱ4f (ɛ∼0) in the Kondo regime. However, the low-frequency limit of dynamical quantities is not consistent with the Fermi-liquid property. It is shown that interpolation of the present results and those by the Fermi-liquid theory is possible. Hence accurate dynamical information is obtained over a wide excitation-frequency range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02071959
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  • 5
    Electronic Resource
    Electronic Resource
    On the absence of magnetic order in intermediate valence compounds (1981)
    Springer
    The European physical journal 40 (1981), S. 293-299 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the mechanism by which the magnetic order is suppressed in intermediate valence compounds. By a diagrammatic perturbation theory in the hybridization interaction, the effective inter-site exchange interaction is derived for the periodic Anderson model. The result includes the effect of charge fluctuations and is valid for arbitrary position of the local electron level relative to the Fermi level. It is shown that the intersite interaction is destructive to magnetic fluctuations with any wavenumber in the case of intermediate valence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01292845
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  • 6
    Electronic Resource
    Electronic Resource
    Self-consistent perturbation theory for dynamics of valence fluctuations (1986)
    Springer
    The European physical journal 65 (1986), S. 29-37 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dynamical property of an intermediate-valence Tm ion in a metallic matrix is investigated by the use of the self-consistent perturbation theory. Both of the fluctuating valence states in Tm have nonzero angular momentum in contrast to Ce and Yb systems. It is shown that the participation of two valence states in the magnetic susceptibility leads to peculiar magnetic properties such as enhanced Korringa-type magnetic relaxation and a systematic deviation from the Curie-Weiss law of the susceptibility. The susceptibility diverges in the zero-temperature limit. The dynamical susceptibility can be fitted by the Lorentzian lineshape very well for a wide frequency and temperature range. The single-particle excitation spectrum is also derived from which the resistivity is calculated. A logarithmic increase of the resistivity with decreasing temperature is found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01308396
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  • 7
    Electronic Resource
    Electronic Resource
    Self-consistent perturbation theory for dynamics of valence fluctuations (1983)
    Springer
    The European physical journal 53 (1983), S. 37-52 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A perturbation-theoretic scheme is developed for dynamics of valence fluctuations in rare-earth systems with unstable 4f shells. The theory is formulated in close analogy to the standard Green-function method for many-body systems but without use of the linked-cluster theorem. This formulation regards hybridization between 4f and conduction-band states as perturbation and naturally incorporates the strong on-site 4f-electron correlation. Some favorable features are: (i) the approximation scheme automatically satisfies conservation laws required for response functions; (ii) realistic 4f-shell structures with crystalline-electric-field effects can be taken into account; (iii) the theory does not have divergence difficulties over the whole temperature range. In the lowest-order self-consistent approximation, explicit formulae for dynamical susceptibilities and 4f-electron density of states are presented. At high temperatures, the theory reproduces previous results obtained by the Mori method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01578246
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  • 8
    Electronic Resource
    Electronic Resource
    Self-consistent perturbation theory for dynamics of valence fluctuations (1984)
    Springer
    The European physical journal 54 (1984), S. 293-303 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dynamical as well as equilibrium properties of model Ce systems are investigated in both the intermediate-valence and nearly integral-valence (Kondo) regimes at finite temperatures. With self-consistent account of hybridization effects between the conduction bands and the highly correlated 4f states, the 4f-electron density of statesρ 4f (ε) and the dynamical magnetic susceptibility χ(ω) are derived. Equilibrium properties such as the static magnetic susceptibility and the averaged 4f-electron number are also computed within the same approximation scheme that neglects intersite interactions between different Ce ions. In the intermediate-valence regime the calculated line-shape of Im χ(ω)/ω is close to the Lorentzian at high temperatures, but at low temperatures there appears an inelastic peak. In the Kondo regime it is shown that a sharp peak inρ 4f (ε) develops at the Fermi level as the temperature decreases. The line-shape of Im χ(ω)/ω is shown to be close to the Lorentzian at all temperatures. The half-width is considerably enhanced over the Korringa value expected for the local-moment system. The temperature dependence of the half-width agrees qualitatively with experimental results in Kondo compounds such as CeB6, CeCu2Si2 and CeAl3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01485826
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  • 9
    Electronic Resource
    Electronic Resource
    Multi-affinity and multi-fractality in systems of chaotic elements with long-wave forcing (1999)
    Springer
    The European physical journal 11 (1999), S. 345-360 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 05.45.-a Nonlinear dynamics and nonlinear dynamical systems - 47.53.+n Fractals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Multi-scaling properties in quasi-continuous arrays of chaotic maps driven by long-wave random force are studied. The spatial pattern of the amplitude X(x,t) is characterized by multi-affinity, while the field defined by its coarse-grained spatial derivative exhibits multi-fractality. The strong behavioral similarity of the X- and Y-fields respectively to the velocity and energy dissipation fields in fully-developed fluid turbulence is remarkable, still our system is unique in that the scaling exponents are parameter-dependent and exhibit nontrivial q-phase transitions. A theory based on a random multiplicative process is developed to explain the multi-affinity of the X-field, and some attempts are made towards the understanding of the multi-fractality of the Y-field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1088/0953-8984/11/2/003
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  • 10
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    Self-consistent perturbation theory for dynamics of valence fluctuations (1984)
    Springer
    Details
    Publication Date: 1984-10-01
    Print ISSN: 0722-3277
    Electronic ISSN: 1431-584X
    Topics: Physics
    Published by Springer
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