Minimal two-band model of the superconducting iron oxypnictides

Raghu, S.; Qi, Xiao Liang; Liu, Chao Xing; Scalapino, D. J.; Zhang, Shou Cheng

doi:10.1103/physrevb.77.220503

Cited by 506 publications

(670 citation statements)

References 12 publications

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“…We also note that the total static susceptibility is symmetric about the line q x = q y ; if peaks in χ −+ (q, ω = 0) are found off this line, for simplicity we will only mention the peak with q x > q y in the discussion. The two-orbital model of Raghu et al 43 was one of the first attempts to model the pnictides from an orbital point of view, and also the first of a number of similar two-orbital models. 42,52,55,77 As it only keeps the xz and yz orbitals, it may be regarded as a minimal orbital model of the system.…”

Section: Resultsmentioning

confidence: 99%

“…A large number of different orbital tightbinding models have therefore been proposed involving between two or five of the Fe 3d orbitals, 42,43,48,51,52,54,56,59,60,64,65,[77][78][79] or also including the As 4p orbitals 45,80 and even orbitals from outside the FeAs planes. 81 Although the existence of superconductivity in these models has been extensively studied, 40,[44][45][46]48,51,53,56,60,63,64,66 the magnetic behaviour remains rather poorly understood.…”

Section: Arxiv:10071949v2 [Cond-matsupr-con] 27 May 2011mentioning

confidence: 99%

“…40,43,48,54,59 In all the proposed models, only on-site terms are included in the interaction Hamiltonian…”

Section: Theorymentioning

confidence: 99%

See 2 more Smart Citations

Magnetic order in orbital models of the iron pnictides

Brydon¹,

Daghofer²,

Timm³

2011

J. Phys.: Condens. Matter

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We examine the appearance of the experimentally-observed stripe spin-density-wave magnetic order in five different orbital models of the iron pnictide parent compounds. A restricted meanfield ansatz is used to determine the magnetic phase diagram of each model. Using the random phase approximation, we then check this phase diagram by evaluating the static spin susceptibility in the paramagnetic state close to the mean-field phase boundaries. The momenta for which the susceptibility is peaked indicate in an unbiased way the actual ordering vector of the nearby meanfield state. The dominant orbitally resolved contributions to the spin susceptibility are also examined to determine the origin of the magnetic instability. We find that the observed stripe magnetic order is possible in four of the models, but it is extremely sensitive to the degree of the nesting between the electron and hole Fermi pockets. In the more realistic five-orbital models, this order competes with a strong-coupling incommensurate state which appears to be controlled by details of the electronic structure below the Fermi energy. We conclude by discussing the implications of our work for the origin of the magnetic order in the pnictides.

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Section: Resultsmentioning

confidence: 99%

Section: Arxiv:10071949v2 [Cond-matsupr-con] 27 May 2011mentioning

confidence: 99%

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Magnetic order in orbital models of the iron pnictides

Brydon¹,

Daghofer²,

Timm³

2011

J. Phys.: Condens. Matter

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“…In order to explain the FS features in IBSC, various two-orbital [39], three-orbital [40,41] and five-orbital [42,43] tight binding models have been proposed. The abundance of available models is induced by the relatively complicated band structure of IBSC materials, which is strongly dependent on the chemical doping [44].…”

Section: Model and Theoretical Backgroundmentioning

confidence: 99%

Multiple phase transitions in Pauli-limited iron-based superconductors

Ptok

2015

J. Phys.: Condens. Matter

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Abstract. Specific heat measurements have been successfully used to probe unconventional superconducting phases in one-band heavy-fermion and organic superconductors. We extend the method to study successive phase transitions in multi-band materials such as iron based superconductors. The signatures are multiple peaks in the specific heat, at low temperatures and high magnetic field, which can lead the experimental verification of unconventional superconducting states with non-zero total momentum.

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“…Both the two-and threeorbital models have been used for the study of the AFM and SC phases of iron-based superconductors. 18,21,22 In order to consider the AFM state, we adopt the following on-site Coulomb interactions:…”

Section: Modelmentioning

confidence: 99%

Coexistence of Antiferromagnetism and Superconductivity in Iron-Based Superconductors

2014

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We theoretically investigate the coexistence of antiferromagnetism and superconductivity in the iron-based superconductors by using the mean-field theory for two-and three-orbital models. We find that both the s+−-wave and s++-wave superconductivity can coexist with antiferromagnetism in the two models. On Dirac Fermi surfaces emerging in the antiferromagnetic phase, a superconducting-gap function has a node for s++ wave but is nodeless for s+− wave. On the other hand, the gap function on non-Dirac Fermi surfaces is either nodeless or accidentally nodal, depending on the parameters of pairing interaction, which is independent of pairing symmetry. IntroductionUnderstanding the phase diagram of iron-based superconductors is a key to clarify the physics of superconductivity of these systems. Parent compounds of iron-based superconductors show an antiferromagnetic (AFM) spin density wave (SDW) below a Néel temperature. With hole or electron doping, magnetization is suppressed and superconductivity emerges. A close relationship of AFM and superconducting (SC) phases indicates that the formation of a Cooper pair is mediated by spin fluctuation, which leads to s +− -wave order 1, 2 where the sign of the gap function on hole Fermi surfaces (FSs) centered at the momentum k = (0, 0) is opposite to that on electron FSs at k=(π,0) and (0,π). On the other hand, it has been proposed that s ++ -wave order, where the two signs are the same, emerges when orbital fluctuation is responsible for superconductivity. 3, 4 s +− and s ++ are possible candidates of SC symmetry in iron-based superconductors.Since the AFM and SC phases are next to each other, the boundary of the two phases may provide useful information on superconductivity of iron-based superconductors. Intriguingly, Ba 1−x K x Fe 2 As 2 , Ba(Fe 1−x Co x ) 2 As 2 and BaFe 2 (As 1−x P x ) 2 show a microscopically coexisting phase of AFM and SC orders, supported by neutron diffraction, 5, 6 X-ray diffraction, 5, 7-9 and NMR 10, 11 experiments.Such a coexistence phase has theoretically been investigated, 12-17 where it is commonly assumed that FSs in a paramagnetic phase consists of a near-circular hole pocket centered at k = (0, 0) and an elliptical electron pocket at k=(π,0) and (0,π). The AFM order with wave vector Q=(π,0) mixes the hole and electron dispersions and a SDW gap is open. Resulting reconstructed FS is completely different from the FS of original paramagnetic phase. In the coexistence phase, it has been pointed out that the SC-gap function on the newly reconstructed

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Minimal two-band model of the superconducting iron oxypnictides

Cited by 506 publications

References 12 publications

Magnetic order in orbital models of the iron pnictides

Magnetic order in orbital models of the iron pnictides

Multiple phase transitions in Pauli-limited iron-based superconductors

Coexistence of Antiferromagnetism and Superconductivity in Iron-Based Superconductors

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