Van Hemmen-Kondo model for disordered strongly correlated electron systems

Magalhães, S. G.; Zimmer, F.M.; Coqblin, B.

doi:10.1103/physrevb.81.094424

Cited by 17 publications

(28 citation statements)

References 29 publications

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“…This model gives a good description of this interplay and appears to be simpler than the previous models, in particular for the treatment of clusters, as we will see later on [52].…”

Section: The Spin Glass-kondo-magnetic Order Competitionmentioning

confidence: 99%

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The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems

Coqblin

2010

Acta Phys. Pol. A

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The interplay between the Kondo effect and magnetism is important in anomalous rare-earth and actinide systems and a brief review of the different Kondo lattice models is presented here. The first studied case is the classical Kondo lattice model with S = 1/2 spins for the 4f localized electrons, which describes the strong competition between the Kondo effect and magnetic ordering leading to small ordering temperatures less than roughly 10 K. The second reviewed case describes the underscreened Kondo lattice model with S = 1 spins for the 5f localized electrons, which can account for the coexistence of both the Kondo effect and the ferromagnetic order and, therefore, the large Curie temperatures observed in actinide compounds like UTe and NpNiSi2; the question of the delocalization of the 5f electrons is also discussed here. The last case describes the competition between the "spin glass" behaviour, the Kondo effect and the magnetic ordering in disordered cerium alloys like CeNixCu1−x or CeRhxPd1−x and several models used for the spin glass state are reviewed, as well as the occurrence of magnetic glass clusters.

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“…This model gives a good description of this interplay and appears to be simpler than the previous models, in particular for the treatment of clusters, as we will see later on [52].…”

Section: The Spin Glass-kondo-magnetic Order Competitionmentioning

confidence: 99%

“…where ξ i and η j are equal to ±1 and are random variables which follow a bimodal distribution [52]. In Eq.…”

Section: The Spin Glass-kondo-magnetic Order Competitionmentioning

confidence: 99%

The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems

Coqblin

2010

Acta Phys. Pol. A

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“…Several cases are described in Ref. [27]. Thus, the more local description [27] given by the van Hemmen model seems to be more adequate here than the average description used for example in the SherringtonKirkpatrick approach [51,53].…”

Section: (1005)mentioning

confidence: 99%

“…where ξ i and η j are equal to ±1 and are random variables which follow a bimodal distribution [27]. We take here both a random SG contribution and a ferromagnetic (FM) one respectively proportional to the parameters J and I 0 .…”

Section: (1005)mentioning

confidence: 99%

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Kondo Lattice Models for Rare-Earth and Actinide Systems

Coqblin

2012

Acta Phys. Pol. A

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We present here some works on the strong competition between the Kondo eect, magnetic order and eventually spin glass or frustration eect in anomalous rare-earth and actinide systems. First, we develop an underscreened Kondo lattice model with S f = 1 spins for the 5f -electrons and we have recently improved it by deriving, by the SchrieerWol transformation, a 5f -band with a nite bandwidth. The underscreened Kondo lattice model can account for properties of some uranium and neptunium compounds, like UTe, Np2PdGa3 or UCu2Si2 which have a large Curie temperature Tc of order 100 K and present also a Kondo behavior. In particular, we can account for the observed maximum of Tc under pressure in UTe and the magnetization curves of NpNiSi2 showing the occurrence of the Kondo eect at low temperatures below Tc. Second, we have studied the properties of disordered cerium alloys like CeCuxNi1−x or CeRhxPd1−x by considering the Kondo eect, a ferromagnetic order and a spin glass behavior described by several approaches. The van Hemmen approach gives a good explanation of the properties of cerium alloys and we are describing the magnetic glass clusters which occur in both spin glass and ferromagnetic phases. Third, we present a new description of a frustrated Kondo lattice model, which can account for the behavior under pressure or doping of some ytterbium compounds like Yb2Pd2Sn and YbAgGe.

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Origin of the Anomalous Electrical Transport Behavior in Fe‐Intercalated Weyl Semimetal T_d‐MoTe₂

et al. 2023

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crystals down to few layers and even monolayer. MoTe 2 is a typical member among TMDCs, hosting fascinating electronic properties, such as extremely large magnetoresistance, [6,7] the emergence of superconductivity, [8] the existence of topological Weyl nodes [9][10][11][12] and semiconducting behavior with a finite band gap. [13] Layered structure with weak interlayer coupling allows for the change of layer stacking order and subsequently gives rise to a structural polymorphism. [14][15][16] In fact, MoTe 2 appears in three kinds of structures: the trigonal prismatic coordinated 2H phase (space group P6 3 /mmc), distorted octahedral coordinated structures, including the monoclinic 1T′ (space group P2 1 /m), and the orthorhombic T d (space group Pmn2 1 ) phases. The 2H phase exhibits semiconducting behavior, while 1T′ and T d phases show semimetallic characters. [13,17,18] As shown in Figure 1a, at room temperature, distortion of in-plane bond give rise to monoclinic unit cell 1T′ phase (tilt angle of ≈93.9°). When decreasing the temperature below 250 K, the shift of layer stacking results an orthorhombic structure. [16,19] In its monoclinic 1T′ phase, monolayer MoTe 2 has been proposed to be topological insulator exhibiting quantum spin Hall effect. [3] While the T d phase demonstrates a number of unique properties, such as extremely large magnetoresistance, nontrivial superconductivity, [20][21][22] switchable ferroelectricity, giant nonlinear Hall effect, and unconventional planar spin Weyl semimetal T d -MoTe 2 has recently attracted much attention due to its intriguing electronic properties and potential applications in spintronics. Here, Fe-intercalated T d -Fe x MoTe 2 single crystals (0 < x < 0.15 ) are grown successfully. The electrical and thermoelectric transport results consistently demonstrate that the phase transition temperature T S is gradually suppressed with increasing x. Theoretical calculation suggests that the increased energy of the T d phase, enhanced transition barrier, and more occupied bands in 1T′ phase is responsible for the suppression in T S . In addition, a ρ α -lnT behavior induced by Kondo effect is observed with x ≥ 0.08, due to the coupling between conduction carriers and the local magnetic moments of intercalated Fe atoms. For T d -Fe 0.15 MoTe 2 , a spin-glass transition occurs at ≈10 K. The calculated band structure of T d -Fe 0.25 MoTe 2 shows that two flat bands exist near the Fermi level, which are mainly contributed by the d yz and d x y 2 2 − orbitals of the Fe atoms. Finally, the electronic phase diagram of T d -Fe x MoTe 2 is established for the first time. This work provides a new route to control the structural instability and explore exotic electronic states for transition-metal dichalcogenides.

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Van Hemmen-Kondo model for disordered strongly correlated electron systems

Cited by 17 publications

References 29 publications

The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems

The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems

Kondo Lattice Models for Rare-Earth and Actinide Systems

Origin of the Anomalous Electrical Transport Behavior in Fe‐Intercalated Weyl Semimetal T_d‐MoTe₂

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Van Hemmen-Kondo model for disordered strongly correlated electron systems

Cited by 17 publications

References 29 publications

The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems

The Kondo Lattice Models and Magnetism for Cerium and Uranium Systems

Kondo Lattice Models for Rare-Earth and Actinide Systems

Origin of the Anomalous Electrical Transport Behavior in Fe‐Intercalated Weyl Semimetal Td‐MoTe2

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Origin of the Anomalous Electrical Transport Behavior in Fe‐Intercalated Weyl Semimetal T_d‐MoTe₂