Normal state bottleneck and nematic fluctuations from femtosecond quasiparticle relaxation dynamics in Sm(Fe,Co)AsO

Mertelj, T.; Stojchevska, L.; Zhigadlo, N. D.; Karpiński, J.; Mihailović, D.

doi:10.1103/physrevb.87.174525

Cited by 10 publications

(10 citation statements)

References 33 publications

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“…It was previously assigned 13,47 to the bottleneck due to the normal-state pseudogap and related to the nematic fluctuations. However, the same reasoning as above can be applied and assign it to the fluctuations of the magneto-structural order parameter.…”

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confidence: 99%

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

et al. 2014

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We systematically investigate temperature-and spectrally-dependent optical reflectivity dynamics in AAs2Fe2, (A=Ba, Sr and Eu), iron-based superconductors parent spin-density-wave (SDW) compounds. Two different relaxation processes are identified. The behavior of the slower process, which is strongly sensitive to the magneto-structural transition, is analyzed in the framework of the relaxation-bottleneck model involving magnons. The results are compared to recent time resolved angular photoemission results (TR-ARPES) and possible alternative assignment of the slower relaxation to the magneto-structural order parameter relaxation is discussed.

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confidence: 99%

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

et al. 2014

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“…For example, the wavelength-dependent femtosecond spectroscopy clearly revealed the magnetic fluctuations at T = 170 K in HoMnO 3 , far above the long-range antiferromagnetic T N = 76 K. 33 A similar technique has been applied to detect the nematic fluctuations above T s in pnictides. [34][35][36] Here we employed polarized ultrafast spectroscopy to elucidate the detailed orientation and temperature dependence of the quasiparticle dynamics in FeSe. As a result of this comprehensive survey, the hidden nematic fluctuations and spin subsystem in FeSe are unveiled.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the hidden nematicity and spin subsystem in FeSe

et al. 2017

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The nematic order (nematicity) is considered as one of the essential ingredients to understand the mechanism of Fe-based superconductivity. In most Fe-based superconductors (pnictides), nematic order is reasonably close to the antiferromagnetic order. In FeSe, in contrast, a nematic order emerges below the structure phase transition at T s = 90 K with no magnetic order. The case of FeSe is of paramount importance to a universal picture of Fe-based superconductors. The polarized ultrafast spectroscopy provides a tool to probe simultaneously the electronic structure and the magnetic interactions through quasiparticle dynamics. Here we show that this approach reveals both the electronic and magnetic nematicity below and, surprisingly, its fluctuations far above T s to at least 200 K. The quantitative pump-probe data clearly identify a correlation between the topology of the Fermi surface and the magnetism in all temperature regimes, thus providing profound insight into the driving factors of nematicity in FeSe and the origin of its uniqueness.

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“…The results of the PDF analysis [21] or the photoexcited carriers [10] and the comparison of the two compounds points to a scenario of local lattice instability (a local atomic displacement mechanism), which sets-in for the Nd1111 system at high temperature. In the low doping level this lattice instability leads to a structural long range T-O phase transition while in the high doping level it cannot acquire long range coherence leading only to an isostructural transition to a sc phase with non correlated local atomic displacements.…”

Section: Discussionmentioning

confidence: 92%

“…Pair distribution function (PDF) studies on two Sm1111 compounds indicate also that the local structure differs significantly from the average structure determined by Bragg diffraction [21]. Finally, the study of the photoexcited carriers in a superconducting SmFe 0.93 Co 0.07 AsO single crystal revealed a 2-fold symmetry breaking in the tetragonal phase related to electronic nematicity around 170 K [10]. All these results point to some lattice distortions that appear in superconducting compounds at much higher temperature than T c .…”

Section: Discussionmentioning

confidence: 94%

Local lattice distortions vs. structural phase transition in NdFeAsO 1 − x F x

Calamiotou¹,

Lampakis²,

Zhigadlo³

et al. 2016

Physica C: Superconductivity and its Applications

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The lattice properties at low temperatures of two samples of NdFeAsO 1-x F x (x=0.05 and 0.25) have been examined in order to investigate possible structural phase transition that may occur in the optimally doped superconducting sample with respect to the non-superconducting low-F concentration compound. In order to detect small modifications in the ion displacements with temperature micro-Raman and high resolution synchrotron powder diffraction measurements were carried out. No increase of the width of the (220) or (322) tetragonal diffraction peaks and microstrains could be found in the superconducting sample from synchrotron XRD measurements. On the other hand, the atomic displacement parameters deviate from the expected behavior, in agreement with modifications in the phonon width, as obtained by Raman scattering. These deviations occur around 150 K for both F dopings, with distinct differences among the two compounds, i.e., they decrease at low doping and increase for the superconducting sample. The data do not support a hidden phase transition to an orthorhombic phase in the superconducting compound, but point to an isostructural lattice deformation. Based on the absence of magnetic effects in this temperature range for the superconducting sample, we attribute the observed lattice anomalies to the formation of local lattice distortions that, being screened by the carriers, can only acquire long-range coherence by means of a structural phase transition at low doping levels.

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Normal state bottleneck and nematic fluctuations from femtosecond quasiparticle relaxation dynamics in Sm(Fe,Co)AsO

Cited by 10 publications

References 33 publications

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides

Unveiling the hidden nematicity and spin subsystem in FeSe

Local lattice distortions vs. structural phase transition in NdFeAsO 1 − x F x

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