Phase diagram of the Holstein-Kondo lattice model at half filling

Nourafkan, Reza; Nafari, N.

doi:10.1103/physrevb.79.075122

Cited by 5 publications

(5 citation statements)

References 25 publications

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“…The latter can be interpreted-in a local moment picture-as the square of an effective fluctuating magnetic moment µ eff (T) (see the discussion in sections 1.2.2 50 The metallization of a Kondo insulator via the electron-phonon coupling was studied theoretically e.g. in the Holstein-Kondo lattice model by Nourafkan and Nafari [407]. 51 See also [155] for a system with large electron-phonon coupling, where optical spectral weight transfers have been quantitatively described without accounting for thermal disorder.…”

Section: Influence Of Vibrations Onto the Electronic Structurementioning

confidence: 99%

Thermoelectricity in correlated narrow-gap semiconductors

Tomczak

2018

J. Phys.: Condens. Matter

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We review many-body effects, their microscopic origin, as well as their impact on thermoelectricity in correlated narrow-gap semiconductors. Members of this class-such as FeSi and FeSb-display an unusual temperature dependence in various observables: insulating with large thermopowers at low temperatures, they turn bad metals at temperatures much smaller than the size of their gaps. This insulator-to-metal crossover is accompanied by spectral weight-transfers over large energies in the optical conductivity and by a gradual transition from activated to Curie-Weiss-like behaviour in the magnetic susceptibility. We show a retrospective of the understanding of these phenomena, discuss the relation to heavy-fermion Kondo insulators-such as CeBiPt for which we present new results-and propose a general classification of paramagnetic insulators. From the latter, FeSi emerges as an orbital-selective Kondo insulator. Focussing on intermetallics such as silicides, antimonides, skutterudites, and Heusler compounds we showcase successes and challenges for the realistic simulation of transport properties in the presence of electronic correlations. Further, we explore new avenues in which electronic correlations may contribute to the improvement of thermoelectric performance.

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Section: Influence Of Vibrations Onto the Electronic Structurementioning

confidence: 99%

Thermoelectricity in correlated narrow-gap semiconductors

Tomczak

2018

J. Phys.: Condens. Matter

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“…DMFT has already been applied to the study of strongly correlated electron-phonon systems and has emerged as one of the most reliable tools for the analysis of these systems 8,9,10,11 . Studies on the normal phase of the Holstein model show that for e-ph couplings, the ground state is metallic with Fermi liquid characteristic, while increasing the coupling a first-order metal-insulator transition takes place.…”

Section: Model and Methodsmentioning

confidence: 99%

Single bipolaronic Transition in Jahn-Teller Model

Nourafkan,

Capone,

Nafari

2009

Preprint

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We investigate the bipolaronic crossover and the pairing transition for a two-orbital model with Jahn-Teller coupling to a two-fold degenerate phonon mode. The evolution from weak to strong coupling is reminiscent of the behavior of the single-band Holstein model: The polaron crossover in which the electrons and phonons become strongly entangled occurs for a weaker coupling than the binding of bipolarons, which gives rise to a metal-insulator transition. Interestingly, a single bipolaronic transition takes place also when the two bands have significantly different bandwidths, as opposed to the case of repulsive Hubbard-like interactions for which an orbital-selective Mott transition has been reported. This behavior is related to the inter-orbital nature of the Jahn-Teller coupling.

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“…Indeed, such strategy has proved fruitful, for instance, in the case of Ce-based superlattices [26], and more recently in the twisted bilayer graphene [27,28], which revealed a wealth of interesting magnetic and superconducting phenomena. We should mention that proximity effects have been studied in the context of the Hubbard model in a layered geometry [29,30], resulting in an induced pairing in the adjacent layers; electron-phonon coupling could also provide the appearance of superconductivity in Kondo insulators, by combining the Holstein model with the PAM [31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Superconducting Kondo phase in an orbitally separated bilayer

Sousa-Júnior

Lima

Costa

et al. 2020

Phys. Rev. Research

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The nature of superconductivity in heavy-fermion materials is a subject under intense debate, and controlling this many-body state is central for its eventual understanding. Here, we examine how proximity effects may change this phenomenon, by investigating the effects of an additional metallic layer on the top of a Kondo lattice and allowing for pairing in the former. We analyze a bilayer Kondo lattice model with an on-site Hubbard interaction, −U , on the additional layer, using a mean-field approach. For U = 0, we notice a drastic change in the density of states due to multiple-orbital singlet resonating combinations. It destroys the well-known Kondo insulator at half filling, leading to a metallic ground state, which, in turn, enhances antiferromagnetism through the polarization of the conduction electrons. For U = 0, a superconducting Kondo state sets in at zero temperature, with the occurrence of unconventional pairing amplitudes involving f electrons. We establish that this remarkable feature is only possible due to the proximity effects of the additional layer. At finite temperatures, we find that the critical superconducting temperature T c decreases with the interlayer hybridization. We have also established that a zero temperature superconducting amplitude tracks T c , which reminisces the BCS proportionality between the superconducting gap and T c .

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Phase diagram of the Holstein-Kondo lattice model at half filling

Cited by 5 publications

References 25 publications

Thermoelectricity in correlated narrow-gap semiconductors

Thermoelectricity in correlated narrow-gap semiconductors

Single bipolaronic Transition in Jahn-Teller Model

Superconducting Kondo phase in an orbitally separated bilayer

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