Electronic structure of heavily electron-doped BaFe$_{1.7}$Co$_{0.3}$As$_2$ studied by angle-resolved photoemission

Sekiba, Y.; Sato, T.; Nakayama, K.; Terashima, K.; Richard, P.; Bowen, J. H.; Ding, H.; Xu, Y. -M.; Li, L. J.; Cao, G. H.; Xu, Z. -A.; Takahashi, T.

doi:10.48550/arxiv.0812.4111

Cited by 6 publications

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“…Four important results are deduced from this analysis: (i) The contribution of the large gap to λ −2 ab (T ) is relatively small in comparison with that observed in Ba 1−x K x Fe 2 As 2 [21]. This may be explained by the fact that the electron doping due to Co substitution reduces the size of the Fermi surface pockets at the Brillouin zone center (where the large gap opens), but leads to substantial enhancement of the pockets at the zone corner (where the small gap develops) [24,25]. (ii) γ λ increases from γ λ ≃ 2.1 at T c to 2.7 at 1.6 K. This increase is consistent with the general trend obtained for various Fe-based HTS [21,26].…”

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confidence: 81%

Superconductivity and Field-Induced Magnetism inSrFe1.75Co0.25As2

et al. 2009

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Using muon-spin rotation, we studied the in-plane (λ ab ) and the out of plane (λc) magnetic field penetration depth in SrFe1.75Co0.25As2 (Tc ≃ 13.3 K). Both λ ab (T ) and λc(T ) are consistent with the presence of two superconducting gaps with the gap to Tc ratios 2∆/kBTc = 7.2 and 2.7. The penetration depth anisotropy γ λ = λc/λ ab increases from γ λ ≃ 2.1 at Tc to 2.7 at 1.6 K. The mean internal field in the superconducting state increases with decreasing temperature, just opposite to the diamagnetic response seen in magnetization experiments. This unusual behavior suggests that the external field induces a magnetic order which is maintained throughout the whole sample volume.

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confidence: 81%

Superconductivity and Field-Induced Magnetism inSrFe1.75Co0.25As2

et al. 2009

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“…Anyhow, here we note that a strong band renormalization in the 122-type compounds is found from recent ARPES studies. [41,48,49,50,51,52] Therefore, the energy scales for possible interband transitions calculated from the LDA (local-density approximation) might deviate from experimental observation. The origin of this midinfrared feature requires further studies.…”

Section: High Energy Featurementioning

confidence: 99%

Optical and Raman spectroscopy studies on Fe-based superconductors

Zhang

Wang

2009

Physica C: Superconductivity

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A brief review of optical and Raman studies on the Fe-based superconductors is given, with special emphasis on the competing phenomenon in this system. Optical investigations on ReFeAsO (Re=rare-earth element) and AFe 2 As 2 (A=alkaline-earth metal) families provide clear evidence for the gap formation in the broken symmetry states, including the partial gaps in the spin-density wave states of parent compounds, and the pairing gaps in the superconducting states for doped compounds. Especially, the superconducting gap has an s-wave pairing lineshape in hole-doped BaFe 2 As 2 . Optical phonons at zone center detected by Raman and infrared techniques are classified for several Fe-based compounds. Related issues, such as the electron-phonon coupling and the effect of spin-density wave and superconducting transitions on phonons, are also discussed. Meanwhile, open questions including the T-dependent mid-infrared peak at 0.6-0.7 eV, electronic correlation, and the similarities/differences between high-T c cuprates and Fe-based superconductors are also briefly discussed. Important results from other experimental probes are compared with optical data to better understand the spin-density wave properties, the superconductivity, and the multi-band character in Fe-based compounds.

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“…It has been suggested based on LDA calculations that the SDW results from nesting of the hole-like Fermi surface (FS) at Γ and electron-like FS at X connected by the wavevector (π, π) [8,9]. However, angle-resolved photoemission spectroscopy (ARPES) reports so far do not seem to converge on the electronic structure at the X-point [10,11,12,13,14,15,16,17,18], and also appear to be inconsistent with LDA calculations, painting a different picture from the earlier work on other pnictide compounds [19]. Given the complexity of the multiband nature of the material, it is important to have a good understanding of the basic character of the band structure before more subtle many-body physics can be understood.…”

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Electronic Structure of the BaFe$_2$As$_2$ Family of Iron Pnictides

Yi,

Lu,

Analytis

et al. 2009

Preprint

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We use high resolution angle-resolved photoemission spectroscopy to study the band structure and Fermi surface topology of the BaFe2As2 iron pnictides. We observe two electron bands and two hole bands near the X-point, (π, π) of the Brillouin zone, in the paramagnetic state for different doping levels, including electron-doped Ba(Co0.06Fe0.94)2As2, undoped BaFe2As2, and hole-doped Ba0.6K0.4Fe2As2. Among these four bands, only the electron bands cross the Fermi level, forming two electron pockets around X, while the hole bands approach but never reach the Fermi level. We show that the band structure of the BaFe2As2 family matches reasonably well with the prediction of LDA calculations after a momentum-dependent shift and renormalization. Our finding resolves a number of inconsistencies regarding the electronic structure of pnictides.

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Electronic structure of heavily electron-doped BaFe$_{1.7}$Co$_{0.3}$As$_2$ studied by angle-resolved photoemission

Cited by 6 publications

References 0 publications

Superconductivity and Field-Induced Magnetism inSrFe1.75Co0.25As2

Superconductivity and Field-Induced Magnetism inSrFe1.75Co0.25As2

Optical and Raman spectroscopy studies on Fe-based superconductors

Electronic Structure of the BaFe$_2$As$_2$ Family of Iron Pnictides

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