Electronic structure of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>BaFe</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>As</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>family of iron-pnictide superconductors

Yi, Ming; Lu, D. H.; Analytis, James; Chu, Jiun‐Haw; Mo, S.-K.; He, Rongrui; Moore, Robert; Zhou, Xianju; Chen, G. F.; Luo, Jianlin; Wang, N. L.; Hussain, Zahid; Singh, David J.; Fisher, I. R.; Shen, Zhi‐Xun

doi:10.1103/physrevb.80.024515

Cited by 134 publications

(109 citation statements)

References 19 publications

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“…Reducing the iron occupancy of the 3d orbital, brings the occupancy of the xy orbital closer to unity, and increases the correlation strength, which in turn strengthens the magnetic moment. This has been observed in ARPES studies of the BaFe 2 As 2 family [28].In the magnetic state, the in-plane resistivity is very anisotropic, as has been shown in optical and transport studies of BaFe 2 As 2 [29,30]. This is a consequence of the strong low energy orbital polarization of the xz and yz orbital [30].…”

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confidence: 56%

Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides

2011

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The iron pnictide and chalcogenide compounds are a subject of intensive investigations due to their high temperature superconductivity.[1] They all share the same structure, but there is significant variation in their physical properties, such as magnetic ordered moments, effective masses, superconducting gaps and T c . Many theoretical techniques have been applied to individual compounds but no consistent description of the trends is available [2]. We carry out a comparative theoretical study of a large number of iron-based compounds in both their magnetic and paramagnetic states. We show that the nature of both states is well described by our method and the trends in all the calculated physical properties such as the ordered moments, effective masses and Fermi surfaces are in good agreement with experiments across the compounds. The variation of these properties can be traced to variations in the key structural parameters, rather than changes in the screening of the Coulomb interactions. Our results provide a natural explanation of the strongly Fermi surface dependent superconducting gaps observed in experiments [3]. We propose a specific optimization of the crystal structure to look for higher T c superconductors.The iron pnictides are Hund's metals [4], where the interaction between the electrons is not strong enough to fully localize them, but it significantly slows them down, so that the low energy quasiparticles have much enhanced mass. These quasiparticles are composites of charge and a fluctuating magnetic moment originating in the Hund's rule interactions which tend to align electrons with the same spin and different orbital quantum numbers when they find themselves on the same iron atom.A central puzzle in this field is posed by the variation of the ordered magnetic moment across the iron pnictides/chalcogenides series. In the fully localized picture the atom resides in a single valence, therefore the ordered moment is equal to the atomic moment (4µ B per iron), possibly reduced by quantum fluctuations. This picture is realized in cuprate superconductors where quantum fluctuations reduce the Cu 2+ moment by 20%. In the fully itinerant weak coupling picture, such as spin density wave (SDW) in chromium metal, the ordered moment is related to the degree of Fermi surface nesting. It is by now clear that the iron pnictides are not well described by either fully localized or fully itinerant picture, nor by the density functional theory (DFT), which greatly overestimates the ordered magnetic moments. It has been advocated that the shortcomings of DFT can be circumvented by incorporating the physics of long wavelength fluctuations [5]. Here we take the opposite perspective. While critical long-wavelength fluctuations certainly play a role near the phase transition lines, we will show that the local fluctuations on the iron atom can account for the correct trend of magnetic moments and correlation strength in iron pnictides/chalcogenide layered compounds.Using the combination of density functional theory and d...

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confidence: 56%

Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides

2011

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“…Band structure calculations predict rather similar electronic structure for all FeSCs (see [162,163] and references therein). ARPES experiments show that it is indeed the case: one can fit the calculated bands to the experiment if it is allowed to renormalize them about 3 times and shift slightly with respect to each other [50,62,164,165]. In this section, I focus first on the most "arpesable" LiFeAs and BKFA compounds, to discuss their electronic structure in details.…”

Section: Electronic Structure and C Tmentioning

confidence: 99%

“…Curiously enough, despite the experimental reports of the propeller like FS, the "parent" FS is still used in a number of theoretical models and as a basis for interpretation of experimental results such as superconducting gap symmetry. Our first interpretation of the propeller-like FS, as an evidence for an additional electronic ordering [40], was based on temperature dependence of the photoemission intensity around X point and on the similarity of its distribution to the parent BFA, but the interpretation based on a shift of the electronic band structure [50] was also discussed. Now, while it seems that the electronic ordering plays a certain role in spectral weight redistribution [44], we have much more evidence for the "structural" origin of the propellers: (1) The propeller-like FS, such as shown Fig.…”

Section: -2mentioning

confidence: 99%

“…From experiment, there are both pro and con arguments on this problem. Pro: any time when the FS nesting is good (BFA [29,50,52] and other parent compounds of 122 family [56][57][58], NaFeAs [70,71]), the SDW is present, and when nesting is poor or absent (superconducting BKFA [38,39], BFCA [28,45], BFAP [56], and stoichiometric LiFeAs [62]), there is no magnetic ordering. Con: Fe 1+y Te shows different spin order, see Fig.…”

Section: Magnetic Orderingmentioning

confidence: 99%

“…As a consequence of good crystal quality and variety of compounds, the 122 family is the most studied by ARPES [37] (see [38][39][40][41][42][43][44] for BKFA, [28,[45][46][47][48][49] for BFCA, [29,[50][51][52][53] for BFA, [31,54] for KFA, [29,55] for CaFe 2 As 2 , [56,57] for BFAP, [58] for EuFe 2 (As 1-x P x ) 2 ). The ARPES spectra well represent the bulk electronic structure of this family, at least, for the hole doped BKFA, BNFA, and BFAP, where the superconducting gap is routinely observed [39,41,59] and is in a good agreement with the bulk probes [43,44].…”

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confidence: 99%

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Iron-based superconductors: Magnetism, superconductivity, and electronic structure (Review Article)

Kordyuk

2012

Low Temperature Physics

209

155

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Angle resolved photoemission spectroscopy (ARPES) reveals the features of the electronic structure of quasitwo-dimensional crystals, which are crucial for the formation of spin and charge ordering and determine the mechanisms of electron-electron interaction, including the superconducting pairing. The newly discovered ironbased superconductors (FeSC) promise interesting physics that stems, on one hand, from a coexistence of superconductivity and magnetism and, on the other hand, from complex multi-band electronic structure. In this review I want to give a simple introduction to the FeSC physics, and to advocate an opinion that all the complexity of FeSC properties is encapsulated in their electronic structure. For many compounds, this structure was determined in numerous ARPES experiments and agrees reasonably well with the results of band structure calculations. Nevertheless, the existing small differences may help to understand the mechanisms of the magnetic ordering and superconducting pairing in FeSC.

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Many Body Perturbation Theory, Dynamical Mean Field Theory and All That

Biermann

Lichtenstein

2017

Handbook of Solid State Chemistry

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This chapter gives an introduction to the theoretical description of strongly correlated materials from first principles. Recent progress in the numerical solution of effective quantum impurity problems within continuous‐time Quantum Monte Carlo schemes has opened the way to efficient dynamical mean field theory‐based simulations of finite‐temperature properties of correlated solids. Here, we review the combinations of dynamical mean‐field theory (DMFT) with density functional theory (DFT) or first‐order many‐body perturbation theory (the so‐called “GW approximation”) from a general functional formulation point of view, putting them into perspective with dual fermion and boson approaches. The goal of these theoretical constructions is to retain the many‐body aspects of local atomic physics within the extended solid. We will describe the current state‐of‐the‐art and future challenges.

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Electronic structure of theBaFe2As2family of iron-pnictide superconductors

Cited by 134 publications

References 19 publications

Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides

Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides

Iron-based superconductors: Magnetism, superconductivity, and electronic structure (Review Article)

Many Body Perturbation Theory, Dynamical Mean Field Theory and All That

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