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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 3683-3685 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A sharp change in the nature of the magnetic ordering has been observed on going from CeSb to CeTe, both of which have NaC1 structures with a small decrease in lattice parameter. This is an interesting example of the way in which hybridization of partially delocalized f electrons with band electrons gives rise to highly unusual magnetic properties which show great chemical sensitivity. In the present paper we apply our previous ab initio treatment of hybridization-induced effects to investigate this striking change in magnetic behavior. We have performed self-consistent warped muffin-tin LMTO band calculations treating the Ce 4f states as resonance states that are constrained to be localized. Compared to CeSb, the anion-derived p bands in CeTe sink well below the Fermi energy, thus strongly changing the band-f hybridization. We have calculated the hybridization dressing of the crystal-field levels and the anisotropic two-ion exchange interaction and compared them with those calculated for CeSb and with experiment. A strong decrease in the two-ion interaction explains the drastic change in observed magnetic behavior between CeSb and CeTe.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5587-5591 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Over the past decade, we have: (1) developed phenomenological theory for the behavior of "well-ordered'' magnetic states of moderately delocalized light rare-earth and actinide systems (characteristically obtaining unusual anisotropic magnetism in agreement with experiment); (2) developed theory and computational technique to synthesize first principles electronic structure information into that phenomenological theory to make it materially predictive. As discussed in this paper, the resulting theory allows us to predict the triggering of an instability from unusual anisotropic, but well-ordered, magnetism to an unstable state. The unstable state can be either of a valence fluctuation type or of what probably is a heavy fermion type, and the detailed way in which these two types of instability is triggered differs.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3385-3387 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To understand the magnetic properties of moderately delocalized light actinide (uranium, neptunium, plutonium) systems, it is necessary to treat correctly the way in which the highly correlated behavior of the f electrons within the actinide ion is linked to the non-f band behavior via the hybridization process. We do this by transforming the hybridization into band-f resonant scattering. We have successfully applied the theory to PuSb by considering both dominant and next-to-dominant scattering channels.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3388-3390 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hybridization of moderately delocalized f electrons with band electrons gives rise to a highly anisotropic two-ion interaction, which, as Siemann and Cooper first showed, accounts well for the unusual magnetic behavior of CeBi. In the present paper it is shown that the even more unusual magnetic behavior of CeSb with a succession of magnetic structures in which the higher-temperature structures (AFP) involve a periodic stacking of nonmagnetic {001} planes alternating with magnetically ordered {001} planes of [001] moment alignment can be understood on the basis of the same hybridization-mediated interionic interaction in the presence of a cubic crystal field (CF) of comparable strength. The tendency to form nonmagnetic planes, which are indeed paramagnetic in nature (Kramers doublets), is found to increase with increasing CF strength, and the stability of the AFP phases at high temperatures is shown to arise from the reconciliation of the magnetic ordering with the CF interactions. The calculations yield first-order phase transitions from a low-temperature type I antiferromagnetic phase to two high-temperature AFP phases. The possibility of a fully nonmagnetic singlet ground state, which, however, is not Kondo-like, also occurs and will be discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5424-5426 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The isostructural uranium monopnictides and monochalcogenides have become prototype systems in actinide research with respect to their unusual magnetic properties. We have investigated the origins in the electronic structure of the variation in magnetic behavior as the degree of 5f-electron localization changes from localized to itinerant on going up the pnictogen or chalcogen column, thus decreasing the U-U separation. We have applied a synthesis of: (1) A phenomenological theory of orbitally driven magnetic ordering which includes both the hybridization-induced and the RKKY exchange interactions on an equal footing, and (2) Ab initio electronic structure calculations, based on the linear-muffin-tin-orbital method, allowing a first-principles evaluation of the parameters entering the model Hamiltonian. We have investigated systematically characteristic trends and changes of the 5f-state resonance width, the hybridization potential, and the hybridization-induced and RKKY exchange interactions with chemical environment, on going down the pnictogen or chalcogen column and on going from the weakly hybridizing pnictides to the more strongly hybridizing chalcogenides.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5194-5196 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For partially delocalized correlated f-electron systems, the key aspect of the electronic behavior is the hybridization of f electrons with the non-f-band electrons. This gives unusual properties including suppressed crystal-field splitting and highly anisotropic ordered magnetism. To improve the general understanding and to make the theory materially predictive, a technique is being developed to evaluate absolutely the parameters of the correlated electron model Hamiltonian, and then to use these to predict observed phenomenology including details of magnetic ordering such as magnetic structures and transitions between structures. The most difficult quantity to predict is the magnetic ordering temperature, among other reasons because it depends on the hybridization strength in a highly nonlinear way. Previously Wills and Cooper have reported on a technique involving a nonconventional electronic structure calculation based on treating the f electron as a resonant state in a solid-state environment to evaluate the hybridization. As an independent check on the evaluation of hybridization, here a conventional tight binding parametrization scheme was used to evaluate the hybridization. These results are compared both with previous results and with experiment for the magnetic ordering temperature and crystal-field dressing of Ce compounds, and the situation introduced by the relative degrees of nonlinearity for the crystal-field and magnetic ordering response to the hybridization strength are commented on.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4161-4163 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Possible 4d magnetism in X/C(0001) (X=Pd, Rh, and Ru) is investigated using the full potential linearized augmented plane wave method. We find that while small magnetic moments of 0.24 and 0.28 μB can survive for Rh and Ru on C(0001), the magnetism of Pd is completely diminished. Due to the unexpectedly strong interfacial interaction between the overlayer and the flat C(0001) substrate, the magnetic moment is very sensitive to changes in the interlayer distances. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5475-5477 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A synthesis of ab initio linear-muffin-tin-orbital (LMTO) electronic structure calculations and a phenomenological model of orbitally driven magnetic ordering has been applied to investigate trends of the effect of hybridization of moderately delocalized f electrons with band electrons on the diverse magnetic behavior across the cerium monochalcogenide series. The parameters entering the Anderson lattice model Hamiltonian are determined from total-energy supercell warped-muffin-tin LMTO calculations with zero, one, and two electrons in the cerium 4f core state. The origins, in the electronic structure, of the variation of the density of states at the Fermi energy, the f-state resonance width, the hybridization potential, the hybridization-dressed crystal-field splitting, and the hybridization-mediated exchange interactions with the chemical environment (anion size) on going down the chalcogen column have been investigated systematically, increasing thus the degree of f-electron localization as the cerium-cerium separation increases.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 2076-2081 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new and analytical thermodynamic model for simple fluids with an intermolecular pair potential consisting of a hard-sphere core and an attractive Yukawa tail is presented. The model yields simple analytic expressions for all thermodynamic properties of the fluid system. The self-consistent numerical results of the present model for the compressibility factor, internal energy, and Helmholtz free energy are in excellent agreement with the Monte Carlo "experiments'' for the whole range of temperatures and densities in which experimental data are available.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 63-64 (1987), S. 121-126 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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