Metal-Insulator Transitions in the Periodic Anderson Model

Sordi, G.; Amaricci, A.; Rozenberg, M. J.

doi:10.1103/physrevlett.99.196403

Cited by 30 publications

(42 citation statements)

References 18 publications

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“…In the dynamical mean-field theory ͑DMFT͒, the self-energy ⌺͑͒ of the impurity site and the effective medium is obtained self-consistently. 20,21 Alternatively, the effective medium can be described by adjustable parameters as in the extended cluster model. [22][23][24] This model was already applied to high-T C superconductors, 22 colossal magnetoresistance materials, 23 and Mott-Hubbard systems.…”

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confidence: 99%

Optical conductivity and x-ray absorption spectra of the Mott-Hubbard compoundsRVO3(R=Sr, Ca, La, and Y)

et al. 2009

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Core-level and valence-band optical spectra provide important information on highly correlated systems. The former corresponds to transitions from the core level to the conduction band, and it is usually related to the unoccupied electronic structure. The later corresponds to transitions from the valence band to the conduction band, and it is sometimes described in terms of the joint density of states. These spectra are usually treated separately due to the differences in the experimental and theoretical methods. We present here a combined description of the core-level and valence-level optical spectra of Mott-Hubbard compounds. In particular, we studied the O 1s x-ray absorption and the optical-conductivity spectra of SrVO 3 -CaVO 3 -LaVO 3 -YVO 3 . The experimental data were analyzed using an extended p-d cluster model solved by an exact diagonalization method. The results show that correlation effects alone cannot account for the experimental structures, and that crystal-field effects and exchange interactions are necessary to explain the spectra. We also show that there is a correspondence between the features in the charge-transfer region of both spectra.

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Section: Calculation Detailsmentioning

confidence: 99%

Optical conductivity and x-ray absorption spectra of the Mott-Hubbard compoundsRVO3(R=Sr, Ca, La, and Y)

et al. 2009

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“…Investigations of these systems have suggested that a crucial control parameter to determine the degree of correlation is the filling of the correlated d orbitals [13][14][15][16][17][18][19], which however does not generally correspond to an integer total number of electrons per site. Moreover, simplified models for these systems display seemingly contradictory results, where the hybridization between a correlated electronic band and a wide band of non-interacting electrons can either forbid [20] or allow [21][22][23][24] In this work we provide an answer to some of these questions. We study the conditions under which a Mott transition takes place, and what are its properties in a a simple, yet generic, model which captures the essential ingredients of the collective behavior of strongly correlated d-electrons hybridized with a band of noncorrelated electrons.…”

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Mott transitions with partially filled correlated orbitals

Amaricci¹,

Medici²,

Capone³

2017

EPL

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We investigate the metal-insulator Mott transition in a generalized version of the periodic Anderson model, in which a band of itinerant electrons is hybridrized with a narrow and strongly correlated band. Using dynamical mean-field theory, we show that the precondition for a Mott transition is an integer total filling of the two bands, while for an integer constant occupation of the correlated band the system remains a correlated metal at arbitrary large interaction strength. We picture the transition at a non-integer filling of the correlated orbital as the Mott localization of the singlet states between itinerant and strongly interacting electrons, having occupation of one per lattice site. We show that the Mott transition is of the first-order and we characterize the nature of the resulting insulating state with respect to relevant physical parameters, such as the charge-transfer energy.Introduction. -Mott localization induced by strong repulsive interaction is intrinsically a physics of commensuration. A paradigmatic example is the Mott-Hubbard transition in the Hubbard model which, in the absence of symmetry breaking, only takes place if the number of correlated electrons equals the number of lattice sites for a single-orbital model [1][2][3][4], or an integer multiple of it in the multi-orbital case [5][6][7][8]. A metal-insulator transition (MIT) occurs as the local repulsion reaches a critical value of the order of the bandwidth, when it becomes energetically convenient for the interacting electrons to localize at any lattice site. The energy gain associated to the electronic motion becomes smaller than the cost associated to charge fluctuations. Hence, the commensurability of the electron density n = N el /N sites naturally emerges as a necessary condition to obtain a Mott insulator. Intuitively this commensuration implies the absence of spare sites where an electron can hop without paying extra electrostatic energy.

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“…The doping driven metal-insulator transition (MIT) in the paramagnetic Mott-Hubbard insulator was the focus of our recent study [16]. The main finding was a qualitatively different scenario for the electron or hole driven transitions.…”

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“…On the other hand, there is also a competing ferromagnetic interaction induced by hole doping. The doped holes need to delocalize to lower their kinetic energy, but they are subject to a strong on-site magnetic binding to the local moments [16]. Therefore, in order to hop, they need the local moments of the neighbor sites to have the same magnetic orientation as the one in its current site.…”

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“…1 we show the DOS of the metallic state that results of lightly doping δ = 3 − n holes into the "parent" Mott insulator state (shown in the right inset). The main features of the metallic state are its mix-valence character and the presence of a quasiparticle peak at the Fermi energy that is flanked by lower and upper Hubbard bands [16]. Within Fermi liquid theory, the key concept is that the one-particle excitations near the Fermi energy, the "quasiparticles", are long lived entities.…”

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Non-Fermi-Liquid Behavior in the Periodic Anderson Model

2008

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We study the Mott metal-insulator transition in the Periodic Anderson Model within Dynamical Mean Field Theory (DMFT). Near the quantum transition, we find a non-Fermi liquid metallic state down to a vanishing temperature scale. We identify the origin of the non-Fermi liquid behavior as due to magnetic scattering of the doped carriers by the localized moments. The non-Fermi liquid state can be tuned by either doping or external magnetic field. Our results show that the coupling to spatial magnetic fluctuations (absent in DMFT) is not a prerequisite to realize a non-Fermi liquid scenario for heavy fermion systems.PACS numbers: 71.10. Hf, 75.30.Mb, 71.27.+a The theoretical understanding of the breakdown of the Fermi liquid paradigm observed in high T c superconductors and heavy fermions systems remains one of the open challenges in strongly correlated physics. These systems show metallic phases with anomalous properties that cannot be accounted for by the Fermi liquid theory, which provides an adequate description of the electronic state of ordinary metals. The reason is intimately related to the strong correlation effects, originated in the localized nature of the d and f orbitals of the experimental compounds [1]. Different ideas have been proposed over the years to try to explain the origin of the non-Fermi liquid (NFL) states, without an absolute consensus so far. However, many of these ideas share a common feature, namely that the central ingredient is the proximity to a quantum phase transition (QPT), or a quantum critical point (QCP) [2]. In that scenario the breakdown of the Fermi liquid occurs in the neighborhood of a T = 0 transition between an ordered phase (e.g. antiferromagnetic) and a paramagnetic one. There, the fluctuations of the order parameter that couple to the electrons are strongest, and are viewed as the origin for the NFL state. Among those approaches we can mention the Hertz-Millis theory, where the paramagnons of the ordered phase "dress" the conduction electrons to produce the NFL features [3]. Another approach is the local quantum critical theory [4, 5], which does not consider the electrons as "bystanders" but emphasizes their role in the screening of the local magnetic moments, via the celebrated Kondo effect. There, the competition between the tendency to formation of local singlets and the long wavelength magnetic fluctuations are to be considered on equal footing. This has been achieved by the formulation of an extension to the Dynamical Mean Field Theory (DMFT) approach [6], called EDMFT [7,8]. DMFT has proven to be a very useful technique to study strongly correlated electron systems when the main physical effects are local [6]. However, it is also recognized that this method lacks a proper description of the spatial magnetic fluctuations which are usually considered a crucial ingredient for the realization of a NFL state. This shortcoming is cured in EDMFT with the incorporation of a bosonic component to the effective mean field. Though that approach has provided useful insig...

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Metal-Insulator Transitions in the Periodic Anderson Model

Cited by 30 publications

References 18 publications

Optical conductivity and x-ray absorption spectra of the Mott-Hubbard compoundsRVO3(R=Sr, Ca, La, and Y)

Optical conductivity and x-ray absorption spectra of the Mott-Hubbard compoundsRVO3(R=Sr, Ca, La, and Y)

Mott transitions with partially filled correlated orbitals

Non-Fermi-Liquid Behavior in the Periodic Anderson Model

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