Degenerate Anderson Model Research Articles

Thermodynamics of theSU(N) Anderson impurity

The thermodynamic Bethe-ansatz equations of the degenerate Anderson model are derived in theU»∞ limit, where the multiple occupation of the localized level is excluded. The Kondo (Coqblin-Schrieffer) limit and the Fermi liquid behavior at lowT are extracted from these equations.

Spectral density and magnetic susceptibility for the asymmetric degenerate Anderson model

With the use of a new diagrammatic formulation, two coupled integral equations for the self-energy functions of the $f$ hole and $f$ particle in the asymmetric degenerate Anderson model are solved numerically. All the diagrams are included in the equations except the cross terms (or the vertex correction). The results for the spectral density function and the magnetic susceptibility show the scaling property described by the renormalization-group theory.

Comparison of the 1/N expansion and Bethe ansatz results for the degenerate Anderson model

The authors find a relation for general N between the conduction band width D of the conventional N-fold-degenerate Anderson model (infinite U) and the cut-off D' imposed on the Bethe ansatz solution of the linear dispersion version of the model. This enables them to compare the results of the 1/N expansion for the ground-state valence nv and the susceptibility chi with the exact Bethe ansatz results. They find complete agreement to leading and next-leading order in 1/N. The expansion to order 1/N is asymptotically exact as nv to 0 with chi varies as nv2, and as nv to 1 with chi varies as exp(1/N(1-nv)). Numerical comparison shows that the expansion to this order gives almost exact results for N=6 and 8 and excellent results for values of N as low as N=2. The authors find a Wilson number W(N) in complete agreement with their earlier calculations for Coqblin-Schrieffer mode.

Susceptibility for the degenerate Anderson model with a strong correlation

The temperature-dependent susceptibility for the degenerate Anderson model with a strong correlation ( U→∞) is calculated numerically on the basis of the Bethe Ansatz treatment.

Bethe ansatz and 1/N expansion results for N-fold degenerate magnetic impurity models

The authors calculate the ground state susceptibility chi 0, to leading and next-leading order in a 1/n expansion, for the N-fold degenerate Anderson model in the integral valent limit. From this and perturbational results they are able to calculate the Wilson numbers W(N), which relate to chi 0 and TK, to first order in 1/N.

Thermodynamics of the degenerate Anderson model

An exact solution is employed to investigate the thermodynamics of the degenerate Anderson model, describing the rare earth magnetic alloys.

A revised diagrammatic technique for the degenerate Anderson model

The Goldstone diagrammatic technique developed by Keiter and Kimball for single impurity Anderson model is reformulated. Instead of having the self-energy functions defined on the real axis as the Brillouin–Wigner theory, we have defined the functions on the complex plane. This avoids the complicated and cumbersome regularization procedure required in the Keiter and Kimball formulation. Most important of all it makes the numerical calculations possible. The exact partition function may be written down in terms of irreducible self-energy diagrams. The Green function and spectral function are derived.

Low Temperature Thermodynamics of the Degenerate Anderson Model with a Strong Correlation

The equilibrium-thermodynamic equations are derived following the Bethe Ansatz treatment of the degenerate Anderson model (strong correlation limit) for rare-earth impurities. The T -linear specific heat is calculated and its ratio to the magnetic susceptibility is discussed.

A new functional integral formalism for the degenerate Anderson model

The authors give a new functional integral formalism for the U= infinity , N-fold degenerate Anderson model based on the form given recently by Coleman (1983). The static approximation, which is believed to be accurate in the large N limit, leads to a Fermi liquid-like description of low-temperature properties of intermediate valent Ce or Yb ions, which is readily extended to the lattice.

Ground state properties of the Anderson model in the limit of large spin-orbit degeneracy

The spin-orbit degenerate Anderson model is investigated in the limit of large spin-orbit degeneracy (N). Low-temperature properties are discussed, yielding the full range of intermediate to local moment behaviour. The relation between ground state susceptibility and valence is examined to leading and next-leading orders in 1/N.

Exact solution of the degenerate Anderson model

On the basis of the Bethe ansatz solution of the degenerate Anderson model the magnetic susceptibility and orbital occupation number of cerium or ytterbium impurities in a metal are calculated in an explicit form.

1Nexpansion for the degenerate Anderson model in the mixed-valence regime

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Hund's‐Rule Effect in Degenerate Anderson Model

AbstractA charge‐transfer operator method is proposed to investigate the Hund's‐rule effect on the formation of local moments in the doubly degenerate Anderson model. The results are compared to the Hartree‐Fock solution.

On the Role of Exchange Coupling in the Atomic Limit of the Orbitally Degenerate Anderson Model

On the Role of Exchange Coupling in the Atomic Limit of the Orbitally Degenerate Anderson Model

Local moment and ferromagnetic state formation in dilute, degenerate d-electron alloys: Ferromagnetic versus antiferromagnetic interactions

In this note the Kim [1] non-degenerate Anderson model (NDAM) of random dilute alloys treatment of local moment and ferromagnetic state formation is generalized to the ten-fold degenerate Anderson model (TDAM) of Siegel and Kemeny [2], Siegel [3,4] and Moriya [12]. We first determine how an impurity state is modified by neighboring impurities. For a simple binary alloy the local electron state at each impurity site depends upon the local distribution of other impurities. Second we derive a TDAM general relationship for the occurrence of a local moment on one impurity and the ferromagnetic ordering of the total impurity spins. Lastly we derive the impurity-impurity TDAM magnetic interaction; for the direct transfer interaction the impurity-impurity magnetic interaction can be ferromagnetic or antiferromagnetic depending upon the fractional occupation of impurity states. At each stage we compare our results with those of Kim's NDAM treatment.

Fermi liquid theory of the degenerate anderson model

Fermi liquid theory of the degenerate anderson model

The Korringa Relation for the Impurity Nuclear Spin-Lattice Relaxation in Dilute Kondo Alloys

We present a proof of the Korringa· relation for the impurity nuclear spin-lattice relaxation of transition-metal impurities in simple metals. Two important mechanisms are considered; the relaxation due to the d-spin fluctuations and the d-orbital fluctuations. By using the 5-fold degenerate Anderson model it is shown that the Korringa relation is valid at low temperatures T<f;_Tx for these two mechanisms in any order of the Coulomb interac­ tion between d-electrons. The proof can be easily extended to the Korringa relation for the Wolff model.