Thermodynamic theory of metal-insulator transitions

Spałek, J.; Honig, J. M.; Acquarone, M.; Datta, Anuradha

doi:10.1016/0304-8853(86)90375-6

Cited by 10 publications

(9 citation statements)

References 4 publications

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“…Second, the continuous increase of (T) across the phase boundary means that electron correlations, not a discontinuous change of the magnetic-moment magnitude, provide the main contribution to the gap. However, a decisive test of our interpretation would be provided by Hall-coefficient measurements in that regime, since in the case of the Mott localization the carrier mass should increase remarkably near the transition, [34][35][36][37][38] while leaving the carrier-concentration constant.…”

Section: Discussionmentioning

confidence: 99%

“…The fundamental reason for this changeover is provided by the near compensation of negative band energy ͑relative to particle localiza-tion͒ of itinerant 3d electrons, and the positive repulsive interaction between them, as described in detail elsewhere. [35][36][37][38] The entropy of itinerant electrons in the Fermi-liquid ͑metal-lic͒ state is small ͑at low T) compared to the entropy change of the same electrons in the localized-moment ͑insulating͒ configuration. Thus, with rising T, the entropy gain achieved by localization drives the metal-insulator transition.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, with rising T, the entropy gain achieved by localization drives the metal-insulator transition. [35][36][37][38] The usual AFI→PI transition takes place at higher temperatures. The second important factor of the Mott localization is the reentrant metallic behavior reached in the high-temperature regime in a continuous manner.…”

Section: Discussionmentioning

confidence: 99%

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Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

et al. 1996

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Electrical resistivity () and Seebeck-coefficient measurements (␣) are reported for NiS 2Ϫx Se x single crystals in the range 0рxр0.71. There is a general trend toward increasing metallicity with increasing x. In the range 0.38рxр0.51 a pronounced rise of with temperature (T) is observed where the antiferromagnetic insulating ͑or antiferromagnetic metallic͒ phase changes over to the paramagnetic insulating phase. The analysis of ␣ vs T curves suggests that in the low-temperature insulating state both holes and electrons participate in charge transport. It is emphasized that the many changes in electrical characteristics occur without significant alterations in the pyrite crystal structure, and that physical properties are greatly altered solely by adjustment of the anion sublattice while the cation sublattice remains intact. The results concerning electrical transport for the samples with 0.38рxр0.55 are interpreted qualitatively on the basis of an onset of the Hubbard splitting into subbands at the transition to the insulating ͑semiconducting͒ state, which takes place in the temperature interval ͑50-100 K͒ upon heating the samples. The metallic state close to the metalsemiconductor boundary is viewed as being an antiferromagnetic semimetal, with an anisotropic Slater gap.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

et al. 1996

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“…It's verified by detailed calculations based on the theory expounded in Ref. [6][7][8][9]. In the theory which describes this effect Spa lek et al [4] did not systematically or numerically explore all the consequences of their theoretical work.…”

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confidence: 96%

“…This included a procedure originally proposed by Spa lek and co-workers [6][7][8] who developed more elementary approach on which the subsequent discussion of this article is based. They considered an assembly of interacting electrons in a solid as a collection of independent quasiparticles that are subject to the framework of solid state physics.…”

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Thermodynamic Analysis of Metal-Insulator Transitions. Effect of Changes in the Density of States Function

Hoehn

Honig

2009

Acta Phys. Pol. A

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Prior theories of metal-insulator transitions by Spa lek et al. were extended to include quartic terms in the temperature and by introducing two different density of state functions. The effects of these extensions on low-temperature metal-insulator transitions and on reentrant metallic behavior in solids have been investigated. PACS numbers: 71.10. Hf, 71.10.Ay, 71.30.+h, 71.45.Gm PreliminariesThere has been continuing interest in the proper treatment of metal-insulator transitions in general, and in the special situation where one encounters reentrant metallic behavior. This is manifested, for example, in the electrical properties of paramagnetic V 2 O 3 doped with small amounts of Cr. With rising temperature T above 180 K, one first observes metallic characteristics; followed by a first-order transition to an insulating state; followed at still higher temperatures by another transition back to the metallic regime [1]. Also, there are instances, such as the NiS 2−y Se y system, that exhibit a metal-insulator transition with rising temperature close to absolute zero [2]; the latter runs contrary to normal observations of an insulator-metal transition with rising T . These unusual situations have been rationalized lately by invoking the dynamic mean field theoretical approach, as championed by a number of research groups [3]. Their principal aim was to generate partial density-of-states curves which match experimental photoemission results, and to note changes concomitant to the occurrence of the metal-insulator transition. While their success is certainly impressive, the theoretical analysis requires considerable computational expertise, such that the fundamentals operative in forcing the electronic changes are not readily discerned. This invites a retrospection to earlier work, beginning with the discussions by Mott This included a procedure originally proposed by Spa lek and co-workers [6-8] who developed more elementary approach on which the subsequent discussion of this article is based. They considered an assembly of interacting electrons in a solid as a collection of independent quasiparticles that are subject to the framework of solid state physics. In the simplest case, one deals with nondegenerate band that is exactly half-filled, and for which -in the insulating state at the zero of temperature -each of the N lattice sites is occupied by one electron. At nonzero temperatures any given lattice site may be empty, accommodate one electron of either spin, or two electrons with paired spins. Double occupancies are energetically disfavored by the Coulomb repulsion U between the two electrons on the same site; electron interactions between more distant neighbors are ignored. Let η represent the probability of encountering a given lattice site in a doubly occupied configuration. Then the total repulsive energy is specified by NUη. Relative to this state, the mobile electrons have an average negative kinetic energyε as they hop between available adjacent sites. However, this process is counteracted by the elec...

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Correlation Effects in the NiS2−xSex System

Honig

1999

Journal of Solid State Chemistry

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Thermodynamic theory of metal-insulator transitions

Cited by 10 publications

References 4 publications

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

Electrical properties ofNiS2−xSexsingle crystals: From Mott insulator to par

Thermodynamic Analysis of Metal-Insulator Transitions. Effect of Changes in the Density of States Function

Correlation Effects in the NiS2−xSex System

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