Selection of the spin-density-wave state

Buker, Donald W.

doi:10.1103/physrevb.24.5713

Cited by 12 publications

(21 citation statements)

References 3 publications

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“…The precise relationship between ⌬ and the magnetization is somewhat complicated. 29,30 To elucidate it, we define the field operator,…”

Section: ͑9͒mentioning

confidence: 99%

“…28 Although the interband Coulomb repulsion causes the excitonic instability, additional interband scattering terms are required to stabilize one of several different density-wave states, such as a SDW or a charge-density wave ͑CDW͒. [29][30][31] Several authors have discussed the SDW state of the pnictides in terms of an excitonic instability of nested electron and hole Fermi pockets without regard to the orbital origin of these bands. [31][32][33][34][35][36] An alternative school of thought emphasizes the importance of the complicated mixing of the iron 3d orbitals at the Fermi energy and of the various interorbital interactions.…”

Section: Introductionmentioning

confidence: 99%

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Spin excitations in the excitonic spin-density-wave state of the iron pnictides

Brydon

Timm

2009

Phys. Rev. B

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Motivated by the iron pnictides, we examine the spin excitations in an itinerant antiferromagnet where a spin-density wave ͑SDW͒ originates from an excitonic instability of nested electronlike and holelike Fermi pockets. Using the random-phase approximation, we derive the Dyson equation for the transverse susceptibility in the excitonic SDW state. The Dyson equation is solved for two different two-band models, describing an antiferromagnetic insulator and metal, respectively. We determine the collective spin-wave dispersions and also consider the single-particle continua. The results for the excitonic models are compared with each other and also contrasted with the well-known SDW state of the Hubbard model. Despite the qualitatively different SDW states in the two excitonic models, their magnetic response shows many similarities. We conclude with a discussion of the relevance of the excitonic SDW scenario to the iron pnictides.

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“…The precise relationship between ⌬ and the magnetization is somewhat complicated. 29,30 To elucidate it, we define the field operator,…”

Section: ͑9͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spin excitations in the excitonic spin-density-wave state of the iron pnictides

Brydon

Timm

2009

Phys. Rev. B

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“…21,27 This can be easily verified if we neglect the overlap between orbitals that belong to different unit cells. In that case, the current-density operator at a point r near R j is given by…”

Section: Order Parametersmentioning

confidence: 93%

Competing chiral and multipolar electric phases in the extended Falicov-Kimball model

2010

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We study the effects of interband hybridization within the framework of an extended FalicovKimball model with itinerant c and f electrons. An explicit interband hybridization breaks the U(1) symmetry associated with the conservation of the difference between the total number of particles in each band. As a result, the degeneracy between multipolar electric and chiral orderings is lifted. We analyze the weak-and strong-coupling limits of the c-f electron Coulomb interaction at zero temperature, and derive the corresponding mean-field quantum phase diagrams at half-filling for a model defined on a square lattice.

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“…We first discuss the case where the interactions that do not support a SDW vanish, and so we set g 1 = g 2b = 0 while fixing the sum of the Coulomb repulsion g cf and the pair-hopping amplitude g 2a to be g cf +g 2a = g SDW = 3.49t c . Since a negative value of g 2a leads to a chargedensity-wave instead of a SDW state, 33,39 we only consider g 2a ≥ 0.…”

Section: Numerical Resultsmentioning

confidence: 99%

Superconducting pairing in the spin-density-wave phase of iron pnictides

Schmiedt¹,

Brydon²,

Timm³

2014

Phys. Rev. B

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Some of the iron pnictides show coexisting superconductivity and spin-density-wave order. We study the superconducting pairing instability in the spin-density-wave phase. Assuming that the pairing interaction is due to spin fluctuations, we calculate the effective pairing interactions in the singlet and triplet channels by summing the bubble and ladder diagrams taking the reconstructed band structure into account. The leading pairing instabilities and the corresponding superconducting gap structures are then obtained from the superconducting gap equation. We illustrate this approach for a minimal two-band model of the pnictides. Analytical and numerical results show that the presence of spin and charge fluctuations in the spin-density-wave phase strongly enhances the pairing. Over a limited parameter range, a px-wave state is the dominant instability. It competes with various states, which have mostly s ± -type structures. We analyze the effect of various symmetry-allowed interactions on the pairing in some detail.

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Selection of the spin-density-wave state

Cited by 12 publications

References 3 publications

Spin excitations in the excitonic spin-density-wave state of the iron pnictides

Spin excitations in the excitonic spin-density-wave state of the iron pnictides

Competing chiral and multipolar electric phases in the extended Falicov-Kimball model

Superconducting pairing in the spin-density-wave phase of iron pnictides

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