Phonon Density of States of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>LaFeAsO</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">F</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:math>

Christianson, A. D.; Lumsden, M. D.; Delaire, Olivier; Stone, M. B.; Abernathy, D. L.; McGuire, Michael A.; Sefat, Athena S.; Jin, Rongying; Sales, B. C.; Mandrus, David; Mun, E. D.; Canfield, Paul C.; Lin, Jiao; Lucas, M. S.; Kresch, M.; Keith, J. Brandon; Fultz, B.; Goremychkin, E. A.; McQueeney, R. J.

doi:10.1103/physrevlett.101.157004

Cited by 75 publications

(54 citation statements)

References 24 publications

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“…8 Efforts were made to estimate the background with a simple Debye model for C(T ). However, the phonon dispersion for LaFeAsO has been measured, 25 and is too complex to be adequately approximated by a linear dispersion relation.…”

Section: Resultsmentioning

confidence: 99%

Magnetotransport properties of single-crystalline LaFeAsO

et al. 2013

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Measurements of magnetization, specific heat, electrical resistivity, Hall effect, and magnetoresistance on single crystalline samples of LaFeAsO grown in a NaAs flux are reported. While this material is known to be a semimetal, the temperature dependence of the electrical resistivity data presented herein is reminiscent of semiconducting behavior and exhibits distinct features associated with a structural transition and spin density wave (SDW) order. Magnetoresistance and Hall coefficient measurements were performed in magnetic fields up to 9 T applied perpendicular to the basal plane using a van der Pauw configuration. The charge carrier density and mobility indicate that electrons are the majority charge carriers and exhibit features indicative of the structural transition and SDW formation. Low temperature X-ray diffraction measurements have confirmed that the structural transition in these samples occurs near 140 K, compared to a transition temperature of 156 K observed in polycrystalline samples. Isotherms of magnetoresistivity measured as a function of magnetic field can be scaled onto a single curve in which the scaling field is a linear function of temperature between 2.2 K and 180 K.

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Section: Resultsmentioning

confidence: 99%

Magnetotransport properties of single-crystalline LaFeAsO

et al. 2013

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“…See for example Ref. [37], where Inelastic Neutron Scattering data are compared to our PDOS. An empirical way to reconcile experiment and theory, by reducing the Fe-As force constant, was proposed in Ref.…”

Section: Discussionmentioning

confidence: 99%

Electron–phonon properties of pnictide superconductors

Boeri¹,

Dolgov²,

Golubov

2009

Physica C: Superconductivity

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In this paper we discuss the normal and superconducting state properties of two pnictide superconductors, LaOFeAs and LaONiAs, using Migdal-Eliashberg theory and density functional perturbation theory. For pure LaOFeAs, the calculated electron-phonon coupling constant λ = 0.21 and logarithmic-averaged frequency ω ln = 206K, give a maximum T c of 0.8 K, using the standard Migdal-Eliashberg theory. Inclusion of multiband effects increases the Tc only marginally. To reproduce the experimental T c , a 5-6 times larger coupling constant would be needed. Our results indicate that standard electron-phonon coupling is not sufficient to explain superconductivity in the whole family of Fe-As based superconductors. At the same time, the electron-phonon coupling in Ni-As based compounds is much stronger and its normal and superconducting state properties can be well described by standard Migdal-Eliashberg theory.

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“…These two points have often been confused, and the failure of continuum plane wave basis states to describe cuprate HTSC has often been used to argue that electron-phonon interactions do not cause HTSC [11]. Because the fraction of carriers involved in percolative paths is small, many negative indications of strong electron-phonon coupling have been found; for example, bulk phonon softening is so small as to be unobservable by neutron scattering at high energies [33]. Therefore it is gratifying that quasiparticle tunneling across a break junction perpendicular to the superconducting copper oxide planes showed 11 phonon features that match precisely with Raman spectra [53], decisively showing that HTSC is indeed caused by electron-phonon interactions along the c-axis, as previously argued from dynamical relaxation experiments [54].…”

Section: Mapping Zzi Percolative Pathsmentioning

confidence: 99%

“…Quite revealing is the fact that the fitted effective charges for "soft layer" rare earth cations in shell models of LSCO and YBCO phonon spectra derived from neutron scattering were inexplicably negative [32]. Neutron scattering has successfully identified Jahn-Teller distortions associated with high-frequency optical modes, and these set the overall scale [30] for T c max , but it is unable to resolve very soft modes [33].…”

Section: Mms and Coarse Grainingmentioning

confidence: 99%

Hard-Wired Dopant Networks and the Prediction of High Transition Temperatures in Ceramic Superconductors

Phillips

2010

J Supercond Nov Magn

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I review the multiple successes of the discrete hard-wired dopant network model ZZIP, and comment on the equally numerous failures of continuum models, in describing and predicting the properties of ceramic superconductors. The prediction of transition temperatures can be regarded in several ways, either as an exacting test of theory, or as a tool for identifying theoretical rules for defining new homology models. Popular "first principle" methods for predicting transition temperatures in conventional crystalline superconductors have failed for cuprate HTSC, as have parameterized models based on CuO 2 planes (with or without apical oxygen). Following a path suggested by Bayesian probability, it was found that the glassy, self-organized dopant network percolative model is so successful that it defines a new homology class appropriate to ceramic superconductors. The reasons for this success in an exponentially complex (non-polynomial complete, NPC) problem are discussed, and a critical comparison is made with previous polynomial (PC) theories. The predictions are successful for the superfamily of all ceramics, including new non-cuprates based on FeAs in place of CuO 2 .

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Phonon Density of States ofLaFeAsO1−xFx

Cited by 75 publications

References 24 publications

Magnetotransport properties of single-crystalline LaFeAsO

Magnetotransport properties of single-crystalline LaFeAsO

Electron–phonon properties of pnictide superconductors

Hard-Wired Dopant Networks and the Prediction of High Transition Temperatures in Ceramic Superconductors

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