scholarly journals Ferromagnetism in the periodic Anderson model. A comparison of spectral density approximation (SDA), modified alloy analogy (MAA) and modified perturbation theory (MPT)

2000 ◽  
Vol 18 (3) ◽  
pp. 385-395 ◽  
Author(s):  
D. Meyer ◽  
W. Nolting
Keyword(s):  
Perturbation Theory ◽  
Spectral Density ◽  
Anderson Model ◽  
Density Approximation ◽  
Periodic Anderson Model

LOCAL MOMENT ORDERING IN PERIODIC ANDERSON MODEL

2001 ◽  
Vol 15 (19n20) ◽  
pp. 2583-2594 ◽  
Author(s):  
A. RAMAKANTH ◽  
W. NOLTING ◽  
G. G. REDDY ◽  
D. MEYER ◽  
S. SCHWIEGER
Keyword(s):  
Magnetic Properties ◽  
Spectral Density ◽  
Anderson Model ◽  
Magnetic Ordering ◽  
High Energy ◽  
Localized States ◽  
Periodic Anderson Model ◽  
Self Energy ◽  
Atomic Limit ◽  
Comparison Of The Results

Strongly correlated electron systems are studied with the help of periodic Anderson model (PAM). The PAM in which highly correlated nondegenerate localized states form a subsystem is considered and the focus of study is on magnetic ordering of electrons in these localized states. In order to study the PAM, which is not amenable to exact solution, two approximate schemes are proposed. The first one is called the spectral density approximation (SDA). Guided by the atomic limit, a two-pole ansatz is made for the localized electron spectral density. The spectral weights and the quasiparticle energies are determined by a moment method. From the spectral density, the spin and energy dependent self-energy is evaluated. A principal limitation of this method is that per ansatz, the quasiparticles are of infinite lifetime. To introduce a finite lifetime, a second approximation scheme is proposed where coherent potential approximation (CPA) is applied to PAM. In order to do CPA, an alloy analogy (AA) is required. In the conventional AA, the concentrations α and the atomic levels E of the fictitious alloy are taken from the atomic limit. Since the interest is in the magnetic properties, this AA is not appropriate. Therefore, a modified AA (MAA) is proposed. In MAA, α and E are obtained using the high energy expansion of the Green's function and the self-energy. In both the approximations, the density of states and the magnetization are selfconsistently evaluated and a phase diagram is obtained. Comparison of the results of the two schemes brings out the effect of quasiparticle damping on the magnetic properties.

scholarly journals “Exhaustion” physics in the periodic Anderson model from iterated perturbation theory

2000 ◽  
Vol 49 (4) ◽  
pp. 459-465 ◽  
Author(s):  
N. S Vidhyadhiraja ◽  
A. N Tahvildar-Zadeh ◽  
M Jarrell ◽  
H. R Krishnamurthy
Keyword(s):  
Perturbation Theory ◽  
Anderson Model ◽  
Periodic Anderson Model

INVESTIGATION OF THE DENSITY OF STATES IN THE NON-HALF-FILLED TWO BAND PERIODIC ANDERSON MODEL

2006 ◽  
Vol 20 (21) ◽  
pp. 3101-3112
Author(s):  
IGOR KOGOUTIOUK ◽  
HANNA TERLETSKA
Keyword(s):  
Spectral Density ◽  
Density Of States ◽  
Anderson Model ◽  
Applied Pressure ◽  
Band Width ◽  
Green Functions ◽  
Periodic Anderson Model ◽  
Consistent Calculation ◽  
Exchange Effects ◽  
Self Consistent

We study density of states in the symmetrical and asymmetrical two-band periodic Anderson models at various band fillings with self-consistent calculation of the orbital occupancies. The application of the improved truncation approximation for irreducible Green functions that takes into account resonance broadening and band shifting inter-orbital exchange effects, resulted in the appearance of four spectral density moments and four- or five-subbands in the density of states depending upon the parameters of the model. It is shown that closing of the hybridization gap can occur as the result of doping, applied pressure, or change of the f-band width.

Superconducting instability in the periodic Anderson model

1998 ◽  
Vol 78 (4) ◽  
pp. 365-374 ◽  
Author(s):  
A. N.Tahvildar-Zadeh, M. H. Hettler, M
Keyword(s):  
Anderson Model ◽  
Periodic Anderson Model

scholarly journals Low-energy scale of the periodic Anderson model

2000 ◽  
Vol 61 (19) ◽  
pp. 12799-12809 ◽  
Author(s):  
Th. Pruschke ◽  
R. Bulla ◽  
M. Jarrell
Keyword(s):  
Anderson Model ◽  
Energy Scale ◽  
Low Energy ◽  
Periodic Anderson Model
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