Magnetic moment evolution and spin freezing in doped BaFe2As2

Pelliciari, Jonathan; Huang, Yaobo; Ishii, Kenji; Zhang, Chenglin; Dai, Pengcheng; Chen, Gen Fu; Xing, Lingyi; Wang, Xiancheng; Jin, Changqing; Ding, Hong; Werner, Philipp; Schmitt, Thorsten

doi:10.1038/s41598-017-07286-6

Cited by 16 publications

(25 citation statements)

References 71 publications

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“…It is known that the composition versus temperature (x vs T ) phase diagram of the transition metal (T M ) substituted Ba(Fe 1−x T M x ) 2 As 2 systems presents an unexpected asymmetry, which concerns the fact that SC is not observed for Cr and Mn substituted samples, that are on the hole-doped side of the phase diagram [6]. The unique aspect related to Mn, or Cr substitution, is the presence of strongly localized magnetic moments at the dopant site [7][8][9], contrasting with the moments observed for Co and K substituted phases, which still present a high degree of itinerancy [10]. Indeed, magnetic moments within the FeAs layers seem to be detrimental to SC, which in other cases has been shown to persist when magnetism is formed between these planes [11,12].…”

Section: Introductionmentioning

confidence: 93%

Anisotropic magnetic excitations and incipient Néel order in Ba(Fe1−xMnx)2As2

et al. 2019

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It is currently understood that high temperature superconductivity (SC) in the transition metal (M ) substituted iron arsenides Ba(Fe1−xM x)2As2 is promoted by magnetic excitations with wave vectors (π, 0) or (0, π). It is known that while a small amount of Co substitution leads to SC, the same does not occur for Mn for any value of x. In this work, magnetic excitations in the iron arsenides Ba(Fe1−xMnx)2As2 (x = 0.0, 0.007, 0.009, 0.08) are investigated by means of Resonant Inelastic X rays Scattering (RIXS) at the Fe L3-edge, for momentum transfer q along the high symmetry Brillouin zone (π, 0) and (π, π) directions. It is shown that with increasing Mn content (x), the excitations become anisotropic both in dispersion and lineshape. Both effects are detected even for small values of x, evidencing a cooperative phenomenon between the Mn impurities, that we ascribe to emerging Néel order of the Mn spins. Moreover, for x = 0.08, the excitations along q (π, 0) are strongly damped and nearly non dispersive. This result suggests that phases of arsenides containing local moments at the FeAs layers, as in Mn or Cr substituted phases, do not support high temperature SC due to absence of the appropriate magnetic excitations.

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Section: Introductionmentioning

confidence: 93%

Anisotropic magnetic excitations and incipient Néel order in Ba(Fe1−xMnx)2As2

et al. 2019

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“…Conventional magnetic experiments probe the system on timescales much longer than τ F . Consequently, they average over the quantum fluctuations, and detect values for the magnitude 2S V that can be considerably smaller than those determined with fast (≈ τ F ) experiments such as PES and x-ray emission spectroscopy (XES), as in the case of the pnictides [12,13,18,19]. The FSM is in general also larger than the spin moment extracted from inelastic neutron scattering, which is a fast experiment, albeit not as fast as PES and XES [13].…”

Section: Resultsmentioning

confidence: 95%

Doping dependence of the magnitude of fluctuating spin moments in the normal state of the pnictide superconductor Sr(Fe1−xCo

Vilmercati

Kim

et al. 2019

Phys. Rev. B

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We report on systematic temperature and doping dependent measurements of the Fe 3s core level photoemission spectra in the normal state of superconducting Sr(Fe 1-x Co x) 2 As 2. The analysis of the Fe 3s spectrum provides an element-specific determination of the mean value of the magnitude of the Fe spin moment measured on the fast (10-16-10-15 s) timescale of the photoemission process. The data reveal the ubiquitous presence in the normal state of Fe spin moments with magnitude fluctuating on short time scales. The data reveal a significant reduction of the magnitude of the effective Fe spin moment on going from the parent to the optimal doped compound. The doping dependence of the magnitude of the spin moment at higher doping level is less clear, being either constant, or even non-monotonic, depending on temperature. This phenomenology indicates the importance of the interaction between spin and itinerant degrees of freedom in shaping the properties of the normal state. These findings reaffirm the complexity of the normal state of 122 Fe-pnictides, which are typically viewed as the least correlated of the high temperature unconventional superconductors.

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“…XES is a photon-in photon-out spectroscopic technique that can be used to detect the spin state in materials 24,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] . The incoming photon (hν=7.140 keV) excites an Fe 1s electron to the continuum with the creation of an unstable core-hole filled by the decay of an Fe 3p electron and emission of a photon.…”

Section: (B)mentioning

confidence: 99%

“…The K β emission line created with this mechanism is composed by a main peak, stemming from the sum of K β 1 and K β 3 and a satellite peak named K β 41,49,55 . The K β peak is directly sensitive to the spin state of the valence band, and using a proper calibration it is possible to extract the value of µ bare [39][40][41][42][43][44][45][46][47]56,64 . This spectroscopy probes the spin states with sensitivity to fast spin fluctuations overcoming the drawback of the quenching of the magnetic moment due to fast quantum fluctuations [57][58][59] .…”

Section: (B)mentioning

confidence: 99%

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Fluctuating magnetism of Co- and Cu-doped NaFeAs

Pelliciari,

Ishi,

Xing

et al. 2021

Preprint

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We report an x-ray emission spectroscopy (XES) study of the local fluctuating magnetic moment (µ bare ) in NaFe 1−x Co x As and NaFe 1−x Cu x As. In NaFeAs, the reduced height of the As ions induces a local magnetic moment higher than Ba 2 As 2 , despite lower T N and ordered magnetic moment.As NaFeAs is doped with Co µ bare is slightly reduced, whereas Cu doping leaves it unaffected, indicating a different doping mechanism: based on electron counting for Co whereas impurity scattering dominates in the case of Cu. Finally, we observe an increase of µ bare with temperature in all samples as observed in electron-and hole-doped BaFe 2 As 2 . Since both Co and Cu doping display superconductivity, our findings demonstrate that the formation of Cooper pairs is not connected with the complete loss of fluctuating paramagnetic moments.

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Magnetic moment evolution and spin freezing in doped BaFe2As2

Cited by 16 publications

References 71 publications

Anisotropic magnetic excitations and incipient Néel order in Ba(Fe1−xMnx)2As2

Anisotropic magnetic excitations and incipient Néel order in Ba(Fe1−xMnx)2As2

Doping dependence of the magnitude of fluctuating spin moments in the normal state of the pnictide superconductor Sr(Fe1−xCo

Fluctuating magnetism of Co- and Cu-doped NaFeAs

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