Local-moment magnetism in superconducting FeTe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>0.35</mml:mn></mml:mrow></mml:msub></mml:math>Se<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>0.65</mml:mn></mml:mrow></mml:msub></mml:math>as seen via inelastic neutron scattering

Xu, Zhijun; Wen, Jinsheng; Xu, Guangyong; Chi, Songxue; Ku, Wei; Gu, Genda; Tranquada, J. M.

doi:10.1103/physrevb.84.052506

Cited by 26 publications

(32 citation statements)

References 49 publications

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“…Interestingly, this estimation has resemblance with results of an inelastic neutron scattering experiment in FeTe 0.35 Se 0.65 where a small fluctuating magnetic moment was found below T c . 42 This system again shows similar features in the Raman spectra as observed in FeSe.…”

supporting

confidence: 71%

Interplay between lattice and spin states degree of freedom in the FeSe superconductor: Dynamic spin state instabilities

et al. 2013

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Polarized Raman-scattering spectra of superconducting, single-crystalline FeSe evidence pronounced phonon anomalies with temperature reduction. A large (∼ 6.5%) hardening of the B1g(Fe) phonon mode is attributed to the suppression of local fluctuations of the iron spin state with the gradual decrease of the iron paramagnetic moment. The ab-initio lattice dynamic calculations support this conclusion. The enhancement of the low-frequency spectral weight above the structural phase transition temperature Ts and its change below Ts is discussed in relation with the opening of an energy gap between low (S = 0) and higher spin states which prevents magnetic order in FeSe. The very narrow phonon line widths compared to observations in FeTe suggests the absence of intermediate spin states in the fluctuating spin state manifold in FeSe.

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supporting

confidence: 71%

Interplay between lattice and spin states degree of freedom in the FeSe superconductor: Dynamic spin state instabilities

et al. 2013

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“…While this result is surprising given expectations on the 7 meV being the resonance directly correlated with superconductivity, this result on powder samples is consistent with recent single crystal experiments which have observed little change in the spectral weight present above the low temperature spin-gap with temperature. 31 These results have been interpreted as strong evidence for the role of local magnetism in the iron telluride superconductors. The low-energy spectral weight present below the low temperature spin gap increases with temperature and at 85 K ( Fig.…”

Section: Resultsmentioning

confidence: 89%

“…38,39 These values are comparable to those obtained by other groups which have probed the dynamics in the superconducting phase. 31 We note that the calibration method here does assume that the elastic cross section is dominated by the incoherent cross section for Fe 1+x Te 0.7 Se 0.3 . It will be important to check this calibration to internal phonons as well as an external vanadium in single crystal samples.…”

Section: Absolute Units and Spectral Weightmentioning

confidence: 99%

Spin fluctuations and superconductivity in powders of Fe1+xTe0.7Se
Stock
¹
,
Rodriguez
²
,
Green
³

2012
Phys. Rev. B
27
1
33
0
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Using neutron inelastic scattering, we investigate the role of interstitial iron on the low-energy spin fluctuations in powder samples of Fe1+xTe0.7Se0.3. We demonstrate how combining the principle of detailed balance along with measurements at several temperatures allows us to subtract both temperature-independent and phonon backgrounds from S(Q, ω) to obtain purely magnetic scattering. For small values of interstitial iron (x = 0.009(3)), the sample is superconducting (Tc=14 K) and displays a spin gap of 7 meV peaked in momentum at wave vector q0=(π,π) consistent with single crystal results. On populating the interstitial iron sites, the superconducting volume fraction decreases and we observe a filling in of the low-energy magnetic fluctuations and a decrease of the characteristic wave vector of the magnetic fluctuations. For large concentrations of interstitial iron (x=0.048( 2)) where the superconducting volume fraction is minimal, we observe the presence of gapless spin fluctuations at a wavevector of q0=(π,0). We estimate the absolute total moment for the various samples and find that the amount of interstitial iron does not change the total magnetic spectral weight significantly, but rather has the effect of shifting the spectral weight in Q and energy. These results show that the superconducting and magnetic properties can be tuned by doping small amounts of iron and are suggestive that interstitial iron concentration is also a controlling dopant in the Fe1+xTe1−ySey phase diagram in addition to the Te/Se ratio.

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“…The spin gap of ∼ 5 meV is clearly visible in the 6 K data. The intensity near the bottom of the dispersion is clearly enhanced in the superconducting phase and the magnetic excitations disperse outwards forming a "U" shape above this spin resonance energy [51,62,70,71]. In the normal state at T = 20 K, the spin resonance fades away and broadens in energy and Q, so that intensity moves into the spin gap; nevertheless, the overall shape of the magnetic excitation spectrum does not appear to change significantly.…”

Section: Datamentioning

confidence: 99%

Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconductingFeTe1−xSex

Schneeloch

Wen

et al. 2016

Phys. Rev. B

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It has recently been demonstrated that dynamical magnetic correlations measured by neutron scattering in iron chalcogenides can be described with models of short-range correlations characterized by particular choices of four-spin plaquettes, where the appropriate choice changes as the parent material is doped towards superconductivity. Here we apply such models to describe measured maps of magnetic scattering as a function of two-dimensional wave vectors obtained for optimally superconducting crystals of FeTe1−xSex. We show that the characteristic antiferromagnetic wave vector evolves from that of the bicollinear structure found in underdoped chalcogenides (at high temperature) to that associated with the stripe structure of antiferromagnetic iron arsenides (at low temperature); these can both be described with the same local plaquette, but with different inter-plaquette correlations. While the magnitude of the low-energy magnetic spectral weight is substantial at all temperatures, it actually weakens somewhat at low temperature, where the charge carriers become more itinerant. The observed change in spin correlations is correlated with the dramatic drop in the electronic scattering rate and the growth of the bulk nematic response on cooling. Finally, we also present powder neutron diffraction results for lattice parameters in FeTe1−xSex indicating that the tetrahedral bond angle tends to increase towards the ideal value on cooling, in agreement with the increased screening of the crystal field by more itinerant electrons and the correspondingly smaller splitting of the Fe 3d orbitals.

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Local-moment magnetism in superconducting FeTe0.35Se0.65as seen via inelastic neutron scattering

Cited by 26 publications

References 49 publications

Interplay between lattice and spin states degree of freedom in the FeSe superconductor: Dynamic spin state instabilities

Interplay between lattice and spin states degree of freedom in the FeSe superconductor: Dynamic spin state instabilities

Spin fluctuations and superconductivity in powders of Fe1+xTe0.7Se
Stock
¹
,
Rodriguez
²
,
Green
³

2012
Phys. Rev. B
27
1
33
0
View full text Add to dashboard Cite

Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconductingFeTe1−xSex

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Local-moment magnetism in superconducting FeTe0.35Se0.65as seen via inelastic neutron scattering

Cited by 26 publications

References 49 publications

Interplay between lattice and spin states degree of freedom in the FeSe superconductor: Dynamic spin state instabilities

Interplay between lattice and spin states degree of freedom in the FeSe superconductor: Dynamic spin state instabilities

Spin fluctuations and superconductivity in powders of Fe1+xTe0.7SeStock1, Rodriguez2, Green3 2012Phys. Rev. B271330View full textAdd to dashboardCite

Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconductingFeTe1−xSex

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Spin fluctuations and superconductivity in powders of Fe1+xTe0.7Se
Stock
¹
,
Rodriguez
²
,
Green
³

2012
Phys. Rev. B
27
1
33
0
View full text Add to dashboard Cite