Two-component Coulomb glass in insulators with a local attraction

Mitchell, Joe; Gangopadhyay, Anirban; Galitski, Victor; Müller, Markus

doi:10.1103/physrevb.85.195141

Cited by 16 publications

(29 citation statements)

References 49 publications

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“…An electronic decoherence-coherence crossover near E F in FeTe upon cooling in this temperature range has been recently predicted by DMFT calculations [38]. Additionally, orbital ordering forming 1D Fe chains has been predicted to be a key ingredient for bicollinear order in FeTe [39], supported by a quantitative Wannier-function analysis [40].…”

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confidence: 70%

Ferro-Orbital Ordering Transition in Iron Telluride Fe1+yTe

Fobes

Zaliznyak

et al. 2014

Phys. Rev. Lett.

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Fe1+yTe with y < ∼ 0.05 exhibits a first-order phase transition on cooling to a state with a lowered structural symmetry, bicollinear antiferromagnetic order, and metallic conductivity, dρ/dT > 0. Here, we study samples with y = 0.09(1), where the frustration effects of the interstitial Fe decouple different orders, leading to a sequence of transitions. While the lattice distortion is closely followed by incommensurate magnetic order, the development of bicollinear order and metallic electronic coherence is uniquely associated with a separate hysteretic first-order transition, at a markedly lower temperature, to a phase with dramatically enhanced bond-order wave (BOW) order. The BOW state suggests ferro-orbital ordering, where electronic delocalization in ferromagnetic zigzag chains decreases local spin and results in metallic transport. In a pattern common with cuprates, iron pnictide and chalcogenide superconductors (FeSC) have parent phases, which, upon cooling, undergo antiferromagnetic (AFM) ordering and structural distortion(s) lowering the high-temperature tetragonal (HTT) paramagnetic lattice symmetry [1,2]. They also host strong magnetic fluctuations, a hallmark of unconventional superconductivity [3]. Recently, there has also been strong experimental evidence of broken electronic symmetry, "nematicity", accompanying, or preceding the magnetic/lattice ordered phase, reminiscent of stripes in cuprates [4]. The physics driving these phenomena, their inter-relation and relation to the superconductivity remain unclear [2].Unlike cuprates, the Fe-based materials have several unfilled 3d bands. Their parent magnetic phases have well-defined Fermi surfaces, indicating a metallic nature [4,5]. Such "weak Mott-ness" and itinerancy, combined with orbital degeneracy entangled with the magnetic and lattice degrees of freedom, leads to the proliferation of theoretical models and approaches: strong coupling where physics is spin-driven [6], weak coupling where it is determined by properties of the electronic Fermi surface [7], or mixed spin-orbital models [8][9][10]. The experimental evidence enabling one to distinguish among these models is, however, still scarce. Here we present such evidence for the case of Fe 1+y Te, the end member of the chalcogenide family of FeSC, where correlation effects are the strongest [11]. By combining the results of bulk characterization of electronic behavior and neutron diffraction data on the temperature evolution of the microscopic structure we are able to disentangle different low-temperature orders and show that the transition to the magnetically-ordered state [12,13], illustrated in Fig. 1(b), is electronically driven through ferro-orbital ordering of zigzag Fe-Fe chains.The iron-chalcogenides Fe 1+y Te 1+x Se x , with T c ≈ 14.5 K at optimal doping, consist of a continuous stacking of Fe square-lattice layers, separated by two halffilled chalcogen (Te,Se) layers [14][15][16]. Predicted by band structure calculations to be a metal [5], nonsuperconducting parent material Fe 1+y T...

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confidence: 70%

Ferro-Orbital Ordering Transition in Iron Telluride Fe1+yTe

Fobes

Zaliznyak

et al. 2014

Phys. Rev. Lett.

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“…Such a description was first devised for the simplest case of N = 1 by Nozières 13,14 in 1974, and generalized to the case of arbitrary N by Nozières and Blandin (NB) 15 in 1980. Their results were confirmed and elaborated by various authors and methods, including NRG, 7,8,[16][17][18][19][20] field-theoretic calculations, 21,22 the Bethe Ansatz, 23,24 conformal field theory (CFT), 25,26 renormalized perturbation theory, 27 and reformulations [28][29][30] and generalizations [31][32][33] of Nozières' approach in the context of Kondo quantum dots.…”

Section: Introductionmentioning

confidence: 79%

Equilibrium Fermi-liquid coefficients for the fully screenedN-channel Kondo model

et al. 2014

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We analytically and numerically compute three equilibrium Fermi-liquid coefficients of the fully screened N -channel Kondo model, namely cB, cT and cε, characterizing the magnetic field and temperature-dependence of the resisitivity, and the curvature of the equilibrium Kondo resonance, respectively. We present a compact, unified derivation of the N -dependence of these coefficients, combining elements from various previous treatments of this model. We numerically compute these coefficients using the numerical renormalization group, with non-Abelian symmetries implemented explicitly, finding agreement with Fermi-liquid predictions on the order of 5% or better.

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“…, since for negative B 0 6 , the Γ 3 ground state does not appear. However, we observe a very narrow yellow region near B 0 4 = −10 −4 , suggesting the entropy 0.5 log 2 of the non-Fermi liquid behavior, which is known to appear at a boundary point between Kondo and non-Kondo phases corresponding to the different fixed points in a two-orbital Anderson model [12,13,14]. In the present case, we obtain the standard Kondo effect in the Γ 5 state, while the singlet state appears in the Γ 1 state.…”

Section: Analysis Of Seven-orbital Anderson Modelmentioning

confidence: 97%

“…In this Appendix, we explicitly show the equations for the matrix elements of the effective interactions Eq. (14). To save 6 space, we do not separately showĨ (0) andĨ (1) , but we exhibit the explicit forms ofĨ aa,aa .…”

Section: Appendix a Matrix Elements Of The Effective Interactionsmentioning

confidence: 99%

Kondo effect in the seven-orbital Anderson model hybridized with Γ8 conduction electrons

Hotta

2018

Physica B: Condensed Matter

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We clarify the two-channel Kondo effect in the seven-orbital Anderson model hybridized with Γ 8 conduction electrons by employing a numerical renormalization group method. From the numerical analysis for the case with two local f electrons, corresponding to Pr 3+ or U 4+ ion, we confirm that a residual entropy of 0.5 log 2, a characteristic of two-channel Kondo phenomena, appears for the local Γ 3 non-Kramers doublet state. For further understanding on the Γ 3 state, the effective model is constructed on the basis of a j-j coupling scheme. Then, we rediscover the two-channel s-d model concerning quadrupole degrees of freedom. Finally, we briefly introduce our recent result on the two-channel Kondo effect for the case with three local f electrons.

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Two-component Coulomb glass in insulators with a local attraction

Cited by 16 publications

References 49 publications

Ferro-Orbital Ordering Transition in Iron Telluride Fe1+yTe

Ferro-Orbital Ordering Transition in Iron Telluride Fe1+yTe

Equilibrium Fermi-liquid coefficients for the fully screenedN-channel Kondo model

Kondo effect in the seven-orbital Anderson model hybridized with Γ8 conduction electrons

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