Intrinsic and structural isotope effects in iron-based superconductors

Khasanov, R.; Bendele, M.; Bussmann‐Holder, A.; Keller, H.

doi:10.1103/physrevb.82.212505

Cited by 25 publications

(23 citation statements)

References 28 publications

(67 reference statements)

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“…We note that the estimated value is much higher than the iron isotope coefficient calculated using T c on the SmFeAsO 0.77 H 0.12 system. 48 Khasanov et al, 50 pointed out that isotope substitution in these systems causes a small structural modification and that inturn affects T c . They did a detailed analysis of the existing studies on the iron-isotope effect using T c and found that the intrinsic isotope effect, which is independent of structural changes, in all of these systems is consistent and of the order of ∼ 0.35 -0.4.…”

Section: Resultsmentioning

confidence: 99%

“…In fact, the electronphonon strength in FeBS is compared to that in MgBr 2 superconductor, where the superconductivity is mediated by electron-phonon coupling. In addition to these theoretical calculations, a large isotope coefficient as high as α Fe ∼ 0.81 has been reported experimentally for different families of FeBS, [46][47][48][49][50][51][52] clearly suggesting that the electron-phonon coupling can not be ruled out in understanding the pairing mechanism in these materials along with other degrees of freedom such as spin and orbital.…”

Section: Introductionmentioning

confidence: 89%

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Iron isotope effect in SmFeAsO0.65 and SmFeAsO0.77H0.12 superconductors: A Raman study

et al. 2016

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We report the inelastic light scattering studies on SmFeAsO0.65 and SmFeAsO0.77H0.12 with iron isotopes namely 54Fe and 57Fe. In both of these systems under investigation we observed a significant shift in the frequency of the phonon modes associated with the displacement of Fe atoms around ∼ 200 cm-1. The observed shift in the Fe mode (B1g) for SmFeAsO0.65 is ∼ 1.4 % and lower in case of SmFeAsO0.77H0.12, which is ∼ 0.65 %, attributed to the lower percentage of isotopic substitution in case of SmFeAsO0.77H0.12. Our study reveals the significant iron isotope effect in these systems hinting towards the crucial role of electron-phonon coupling in the pairing mechanism of iron based superconductors.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 89%

Iron isotope effect in SmFeAsO0.65 and SmFeAsO0.77H0.12 superconductors: A Raman study

et al. 2016

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“…Upon the application of pressure, its T c increases up to 37 K at p ~ 7 GPa 9 10 . Although there are experimental and theoretical studies showing the unconventional superconductivity in the FeSCs 11 12 13 14 15 , the Fe isotope effect has been observed 16 17 18 19 20 which implies the role of phonons may not be sorely excluded. On the other hand, SnO is comprised of nonmagnetic atoms so magnetism-related mechanism can not account for the electron pairing in SnO.…”

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confidence: 99%

Phase diagram of the layered oxide SnO: GW and electron-phonon studies

Chen

Jeng

2015

Sci Rep

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First-principles calculations are performed to study the electronic properties and the electron-phonon interactions of the layered oxide semiconductor SnO. In addition to the high hole mobility that makes SnO a promising material in electronics, it has recently been reported that the semimetallic phase under pressure is superconducting. The superconducting Tc curve exhibits a dome-like feature under pressure and reaches the maximum of 1.4 K at p = 9.2 GPa. Both its crystal structure and the dome-like Tc curve are reminiscent of the Fe-based superconductor FeSe. Motivated by this observation, we investigate the electronic, phonon, and their interactions in SnO using first-principles schemes. GW approximation is adopted to correct the underestimated band gaps, including real and continuous band gaps in the semiconducting and semimetallic phases. The phase diagram showing the semiconductor-to-semimetal transition and the Tc curve has been successfully reproduced. Detailed analysis of the electron-phonon interactions demonstrate the importance of the out-of-plane motions of O atoms and the Sn-s lone pairs for the superconductivity to occur. Our method combining GW and e-ph calculations can be further extended to the study of other materials that undergo insulator-to-superconductor phase transition.

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“…However, his approach has been questioned by Bussmann-Holder and Keller12 that claimed that an inversion of the Fe-IE exponent could not occur. More recently, Khasanov et al 13 tried solving the discrepancy in the Fe-IE measurements by decomposing the exponent in two terms: one associated to structural changes and one intrinsic. They also pointed out that the Fe isotope substitution may induce small structural changes which, in turn, may affect T c .…”

mentioning

confidence: 99%

Iron Isotope Effect and Local Lattice Dynamics in the (Ba, K)Fe2As2 Superconductor Studied by Temperature-Dependent EXAFS

Chu

Cheng

Chu

et al. 2013

Sci Rep

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Currently available investigations of the isotope effect in Fe-based superconductors are all based on macroscopic resistivity and susceptibility measurements and results are highly controversial. Here we present an investigation of the Fe isotope effect in the (Ba, K)Fe2As2 superconductor by temperature-dependent EXAFS in the framework of Einstein model. This method separates the static structural isotope contribution and the local lattice isotope contribution. Results point out the isotope substitution has a negligible effect on inter-atomic distances. On the contrary, both the local vibrations of the Fe-As and the Fe-Fe bonds show strong iron isotope dependence, which is a marker of an “intrinsic” isotope effect. This bulk iron isotope contribution to the local lattice dynamics suggests the local phonons play an important role in the (Ba, K)Fe2As2 superconductor and a three-dimensional electron-phonon interaction should be considered to understand the superconducting mechanism of iron-based superconductors.

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Intrinsic and structural isotope effects in iron-based superconductors

Cited by 25 publications

References 28 publications

Iron isotope effect in SmFeAsO0.65 and SmFeAsO0.77H0.12 superconductors: A Raman study

Iron isotope effect in SmFeAsO0.65 and SmFeAsO0.77H0.12 superconductors: A Raman study

Phase diagram of the layered oxide SnO: GW and electron-phonon studies

Iron Isotope Effect and Local Lattice Dynamics in the (Ba, K)Fe2As2 Superconductor Studied by Temperature-Dependent EXAFS

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