Electron–phonon properties of pnictide superconductors

Boeri, Lilia; Dolgov, O. V.; Golubov, Alexandre Avraamovitch

doi:10.1016/j.physc.2009.03.020

Cited by 46 publications

(44 citation statements)

References 53 publications

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“…This is too small to reproduce the T c of the 122s. This mismatch between the electron-phonon coupling constant λ and the expected T c is similar to calculations done on several 1111 pnictides where λ ∼ 0.17 − 0.21 predict a T c of a few Kelvin at most 32 . A λ tr ∼ 0.12 is also much smaller than the λ tr = 1.53 reported for PrFeAsO 1 .…”

Section: Discussionsupporting

confidence: 87%

High-temperature resistivity in the iron pnictides and the electron-doped cuprates

et al. 2011

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We measured the high temperature (up to 800 K) resistivity of several dopings of SrFe2−x(Ni,Co)xAs2 (122) and compared the results with similar measurements on electron-doped cuprates. We find that the Sr-122 pnictide resistivity saturates above 500 K at around 400 − 700 µΩ·cm, consistent with the Mott-Ioffe-Regel (MIR) limit and in contrast to the MIR violating behavior of the hole-doped cuprates and our measurements on electrondoped cuprates. This supports the view that electronic correlations in the ferropnictides may be weaker than in the cuprates.

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Section: Discussionsupporting

confidence: 87%

High-temperature resistivity in the iron pnictides and the electron-doped cuprates

et al. 2011

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“…As was shown in [15], the superconducting transition temperatures T C for different types of iron-based superconductors correlate with the total density of states at the Fermi level. This fact and the strong Fe isotope effect, which was reported by [16] supports the phonon-mediated coupling importance [17] in these compounds [15,18]. The electron-phonon coupling is enhanced by an extended van Hove singularity [19] which was shown for iron pnictides and, in particular, for LiFeAs [20].…”

supporting

confidence: 68%

Investigation of LiFeAs by means of “break-junction” technique

et al. 2012

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In our tunneling investigation using Andreev superconductor -normal metal -superconductor contacts on LiFeAs single crystals we observed two reproducible independent subharmonic gap structures at dynamic conductance characteristics. From these results, we can derive the energy of the large superconducting gap ∆L = (2.5 ÷ 3.4) meV and the small gap ∆S = (0.9 ÷ 1) meV at T = 4.2 K for the T local C ≈ (10.5 ÷ 14) K (the contact area critical temperature which deviation causes the variation of ∆L). The BCS-ratio is found to be 2∆L/kBTC = (4.6 ÷ 5.6), whereas 2∆S/kBTC ≪ 3.52 results from induced superconductivity in the bands with the small gap.The new class of superconducting rare-earth oxypnictides [1] is still not completely understood and therefore requires further investigation. The layered LiFeAs (111-system) [2] is one of the few stoichiometric Febased pnictides which shows neither magnetic nor structural transition but becomes superconducting at 18 K [3,4]. Band-structure calculations [5,6,7] show the Fermi surfaces for 111-system to be comprised of quasitwo-dimensional (2D) hole cylinders centered at the Γ-point and electron ones at the M-point of the first Brillouin zone that can be considered as two effective bands (so called minimal two-band model) [8,9]. The total density of states at the Fermi level is formed mainly by Fe 3d-states [10,11,12,13,14]. As was shown in [15], the superconducting transition temperatures T C for different types of iron-based superconductors correlate with the total density of states at the Fermi level. This fact and the strong Fe isotope effect, which was reported by [16] supports the phonon-mediated coupling importance [17] in these compounds [15,18]. The electron-phonon coupling is enhanced by an extended van Hove singularity [19] which was shown for iron pnictides and, in particular, for LiFeAs [20]. In this work, we present an investigation of the superconducting properties of LiFeAs single crystals by means of Andreev spectroscopy of superconductor -normal metal -superconductor (SNS) contacts, and the corresponding superconducting gaps.The LiFeAs single crystals were obtained by self-flux method. The synthesis and investigation of the composition and properties are detailed in [21]. A mixture of small lumps of the Li metal and powders of Fe and As in a molar ratio of Li : Fe : As = 3 : 2 : 3 was 1) e-mail: kuzmichev@mig.phys.msu.ru placed into an alumina crucible. All work on the reactive mixture preparation was carried out in a dry box under argon atmosphere. The crucible was inserted into a niobium container, which was welded in argon at 1.5 atm. The sealed Nb container was enclosed in a quartz ampoule. The sample was heated up to 1363 K, kept at this temperature and slowly cooled down to 873 K. At this temperature ampoule was extracted from the furnace and cooled in open air. The LiFeAs single crystals in the form of thin plates with lateral dimensions of (12 ± 6) × (12 ± 6) × (0.1 ± 0.05) mm 3 were separated from flux mechanically. According to the XRD, EDX, ICP MS, a...

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“…For instance, EPC mechanism can get a reasonable T C of the hcp iron under pressure, but can not explain the rapid disappearance of SC above 30 GPa 7,59,60 . For the iron pnictide superconductors 8 , Boeri et al 61,62 and Mazin et al 63 pointed out that the EPC in the system is intrinsically weak, but can be enhanced strongly by magnetism 64 . Although EPC is still not enough to explain the high critical temperature, it is strong enough to have a non-negligible effect on SC.…”

Section: Other Potential Superconducting Axm3mentioning

confidence: 99%

Prediction of Superconductivity in 3d Transition-Metal Based Antiperovskites via Magnetic Phase Diagram

Shao

Tong

et al. 2014

J. Phys. Soc. Jpn.

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We theoretically studied the electronic structure, magnetic properties, and lattice dynamics of a series of 3d transition-metal antiperovskite compounds AXM3 by density function theory. Based on the Stoner criterion, we drew the magnetic phase diagram of carbon-based antiperovskites ACM3. In the phase diagram, compounds with non-magnetic ground state but locating near the ferromagnetic boundary are suggested to yield sizeable electron-phonon coupling and behave superconductivity. To approve this deduction, we systematically calculated the phonon spectra and electron-phonon coupling of a series of Cr-based antiperovskites ACCr3 and ANCr3. The results show that AlCCr3, GaCCr3, and ZnNCr3 could be moderate coupling BCS superconductors. The influence of spin fluctuation on superconductivity are discussed. Furthermore, other potential superconducting AXM3 including some new Co-base and Fe-based antiperovskite superconductors are predicted from the magnetic phase diagram.

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Electron–phonon properties of pnictide superconductors

Cited by 46 publications

References 53 publications

High-temperature resistivity in the iron pnictides and the electron-doped cuprates

High-temperature resistivity in the iron pnictides and the electron-doped cuprates

Investigation of LiFeAs by means of “break-junction” technique

Prediction of Superconductivity in 3d Transition-Metal Based Antiperovskites via Magnetic Phase Diagram

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