Lokal'nye momenty i lokalizovannye sostoyaniya

Anderson, Philip W.

doi:10.3367/ufnr.0127.197901b.0019

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…The quantum statistical theory of systems with strong inter-electron correlations began to develop intensively when the main features of early semi-phenomenological theories were formulated in the language of simple model Hamiltonians. Both the Anderson model, 162,163 which formalized the Friedel theory of impurity levels, and the Hubbard model, [164][165][166][167][168][169] which formalized and developed early theories by Stoner, Mott, and Slater, equally stress the role of inter-electron correlations. The Hubbard Hamiltonian and the Anderson Hamiltonian (which can be considered as the local version of the Hubbard Hamiltonian) play an important role in the electron's solid-state theory.…”

Section: The Problem Of Magnetism Of Itinerant Electronsmentioning

confidence: 99%

Statistical Mechanics and the Physics of Many-Particle Model Systems

Kuzemsky

2016

124

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The development of methods of quantum statistical mechanics is considered in light of their applications to quantum solid-state theory. We discuss fundamental problems of the physics of magnetic materials and the methods of the quantum theory of magnetism, including the method of two-time temperature Green's functions, which is widely used in various physical problems of many-particle systems with interaction. Quantum cooperative effects and quasiparticle dynamics in the basic microscopic models of quantum theory of magnetism: the Heisenberg model, the Hubbard model, the Anderson Model, and the spin-fermion model are considered in the framework of novel self-consistent-field approximation. We present a comparative analysis of these models; in particular, we compare their applicability for description of complex magnetic materials. The concepts of broken symmetry, quantum protectorate, and quasiaverages are analyzed in the context of quantum theory of magnetism and theory of superconductivity. The notion of broken symmetry is presented within the nonequilibrium statistical operator approach developed by D.N. Zubarev. In the framework of the latter approach we discuss the derivation of kinetic equations for a system in a thermal bath. Finally, the results of investigation of the dynamic behavior of a particle in an environment, taking into account dissipative effects, are presented.

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Section: The Problem Of Magnetism Of Itinerant Electronsmentioning

confidence: 99%

Statistical Mechanics and the Physics of Many-Particle Model Systems

Kuzemsky

2016

124

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“…The result depends on the intra atomic repulsion between the d electrons, which is characterized by the Anderson-Hubbard parameter U, and on position of the impurity level in the energy band of the metal; creation of uncompensated magnetic moment is facilitated at a low density of conduction electrons and low degree of bond covalency. 63 For covalent bonding to occur, the energetically favorable situation must involve orbital motion of electrons with the maximum electron density in the region between positively charged nuclei (J < 0), so covalent bonding produces a spin singlet. As the bond covalency in M 3+ -An-M 3+ and M 4+ -An-M 4+ (An is an anion) increases in the order of anions F -, O 2-, S 2-, Se 2-, the exchange integral J also increases.…”

Section: Spin Interaction In Semiconductorsmentioning

confidence: 99%

Spintronics and spintronics materials

et al. 2004

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The review concerns the fundamentals of spintronics (spin transport electronics). The material covers spin spin interactions and spin relaxation in semiconductors as well as spin and spin injection related effects in the condensed matter. Examples of promising spintronic de vices are given, requirements for spintronic materials are formulated, methods of synthesis of spintronic materials are described, and the physicochemical properties of some materials are characterized. Organic spintronic materials are briefly outlined and the state of the art in the field of research on inhomogeneous magnetic semiconducting materials possessing high tem perature ferromagnetism is described. The emphasis is placed on the chemical bonding and electronic structure of magnetic impurities in semiconductors, consideration of the nature of ferromagnetism, and on the character of exchange interactions between localized spins in novel spintronic materials.

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“…A possibility of localization due to off-diagonal disorder was discussed in connection with the problem of formation of an impurity band in a semiconductor, which in fact stimulated the creation of the localization theory. 38 An isolated impurity in a semiconductor can generate a state with energy E 0 within the band gap. When the concentration of such impurities is finite, they form an impurity band, which is described in the site representation by the Anderson model with off-diagonal disorder ͑sometimes this is termed the Lifshitz model 5…”

Section: Localization In the Case Of Off-diagonal Disordermentioning

confidence: 99%

“…38 An isolated impurity in a semiconductor can generate a state with energy E 0 within the band gap. When the concentration of such impurities is finite, they form an impurity band, which is described in the site representation by the Anderson model with off-diagonal disorder ͑sometimes this is termed the Lifshitz model…”

Section: Localization In the Case Of Off-diagonal Disordermentioning

confidence: 99%

Scaling near the upper critical dimensionality in the localization theory

Suslov

1998

J. Exp. Theor. Phys.

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The phenomenon of upper critical dimensionality d c2 has been studied from the viewpoint of the scaling concepts. The Thouless number g(L) is not the only essential variable in scale transformations, because there is the second essential parameter connected with the off-diagonal disorder. The investigation of the resulting two-parameter scaling has revealed two scenarios, and switching from one to another scenario determines the upper critical dimensionality. The first scenario corresponds to the conventional one-parameter scaling and is characterized by the parameter g(L) invariant under scale transformations when the system is at the critical point. In the second scenario, the Thouless number g(L) grows at the critical point as L dϪd c2 , which leads to a violation of the Wegner relation sϭ(dϪ2) between the critical exponents for conductivity s and localization radius , which takes the form sϭ(d c2 Ϫ2). The resulting formulas for g(L) are in agreement with the symmetry theory suggested in a previous publication, I. M. Suslov, Zh. É ksp. Teor. Fiz. 108, 1686 ͑1995͒ ͓JETP 81, 925 ͑1995͔͒. A more rigorous version of Mott's argument concerning localization due to topological disorder has been proposed.

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Lokal'nye momenty i lokalizovannye sostoyaniya

Cited by 8 publications

References 4 publications

Statistical Mechanics and the Physics of Many-Particle Model Systems

Statistical Mechanics and the Physics of Many-Particle Model Systems

Spintronics and spintronics materials

Scaling near the upper critical dimensionality in the localization theory

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