Angular dependence of x-ray absorption spectrum for field-aligned iron-based superconductors

Chang, B. C.; You, Y. B.; Shiu, T. J.; Tai, M. F.; Ku, H. C.; Hsu, Y. Y.; Jang, Ling‐Yun; Lee, J. F.; Wei, Zhiguo; Ruan, Keqing; Li, X. G.

doi:10.1103/physrevb.80.165108

Cited by 22 publications

(24 citation statements)

References 15 publications

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“…The prepeak feature A (∼ 7112 eV) is the result of a direct quadrupole transition to unoccupied 3d states that are hybridized with Te 4p orbitals. The edge feature B (∼ 7118 eV) is governed by 1s → 4p transition, which is close to the one for a reference Fe 2+ standard, 33,34 indicating the Fe 2+ state. The peak-like feature C (∼ 7120 eV) should be driven by the 1s → 4p states admixed with Te d states, and the feature D is mainly due to multiple scattering of the photoelectrons with the nearest neighbors.…”

Section: Resultssupporting

confidence: 72%

Anomalous Hall effect in the van der Waals bonded ferromagnet Fe3−xGeTe2

et al. 2018

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We report anomalous Hall effect (AHE) in single crystals of quasi-two-dimensional Fe3−xGeTe2 (x ≈ 0.36) ferromagnet grown by the flux method which induces defects on Fe site and bad metallic resistivity. Fe K-edge x-ray absorption spectroscopy was measured to provide information on local atomic environment in such crystals. The dc and ac magnetic susceptibility measurements indicate a second-stage transition below 119 K in addition to the paramagnetic to ferromagnetic transition at 153 K. A linear scaling behavior between the modified anomalous Hall resistivity ρxy/µ0H ef f and longitudinal resistivity ρ 2 xx M/µ0H ef f implies that the AHE in Fe3−xGeTe2 should be dominated by the intrinsic Karplus-Luttinger mechanism rather than the extrinsic skew-scattering and side-jump mechanisms. The observed deviation in the linear-M Hall conductivity σ A xy below 30 K is in line with its transport characteristic at low temperatures, implying the scattering of conduction electrons due to magnetic disorder and the evolution of the Fermi surface induced by possible spin-reorientation transition.

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Section: Resultssupporting

confidence: 72%

Anomalous Hall effect in the van der Waals bonded ferromagnet Fe3−xGeTe2

et al. 2018

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“…Based on polarized Fe K-edge x-ray absorption of FeSe x crystals, pre-edge peak A and feature B show a larger density of states of corresponding to unoccupied Fe 3d-Se 4p and Fe 4p-Se 4d hybrid bands, respectively, along the c axis. 33,34 The larger compression along the c axis, accompanied by an increased FeSe 4 tetrahedral distortion of Fe 1.01 Se upon pressurization, suppresses the Fe 3d-Se 4p and Fe 4p-Se 4d hybridization, particularly along the c axis, and consequently leads to a decreased intensity of pre-edge peak A and feature B. 35 T c of Fe 1.01 Se increased to 34-37 K on applying P 5.5-9 GPa and then slowly decreased under P from 10 to 22 GPa.…”

Section: Resultsmentioning

confidence: 99%

Pressure dependence of the electronic structure and spin state in Fe1.01Se superconductors probed by x-ray absorption and x-ray emission spectroscopy

et al. 2011

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Pressure dependence of electronic structures and spin states of iron-chalcogenide Fe 1.01 Se superconductors up to ∼66 GPa has been investigated with x-ray emission spectra and x-ray absorption spectra with partial-fluorescence yield. The intensity of the pre-edge peak at energy of ∼7112.7 eV of the Fe K-edge x-ray absorption spectrum of Fe 1.01 Se decreases progressively with pressure up to ∼10 GPa. A new prepeak at energy of ∼7113.7 eV develops for pressure above ∼13 GPa, indicating formation of a new phase. The experimental and the calculated Fe K-edge absorption spectra of Fe 1.01 Se using the FDMNES code agree satisfactorily. The larger compression accompanied by significant distortion around the Fe atoms along the c axis in Fe 1.01 Se upon applying pressure suppresses the Fe 3d-Se 4p and Fe 4p-Se 4d hybridization. The applied pressure suppresses the nearest-neighbor ferromagnetic superexchange interaction and enhances spin fluctuations on the Fe sites in Fe 1.01 Se. A discontinuous variation of the integrated absolute difference values of the Kβ emission line was observed, originating from a phase transition of Fe 1.01 Se for a pressure >12 GPa. Fe 1.01 Se shows a small net magnetic moment of Fe 2+ at ambient pressure, probably arising from strong Fe-Fe spin fluctuations. The satellite line Kβ was reduced in intensity upon applying pressure and became absent for pressure >52 GPa, indicating a continuous reduction of the spin moment of Fe in Fe 1.01 Se superconductors. The experimental results provide insight into the spin state of Fe 1.01 Se superconductors under pressure.

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“…A possible explanation is that this modulation for the K-doped samples might be ascribed to differences in the dd-interactions between the two types of hole-doping. [23][24][25][26]30,31]. In the supplemental material we include calculations of our HERFD-XANES spectra showing that the A peak has mostly dipole character and that it arises when the four As nearest neighbours conforming the FeAs 4 tetrahedra are included in the structure, which corroborates its origin in the Fe 3d -As 4p mixing.…”

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confidence: 89%

Evidence of Mott physics in iron pnictides from x-ray spectroscopy

et al. 2017

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X-ray emission and absorption spectroscopies are jointly used as fast probes to determine the evolution as a function of doping of the fluctuating local magnetic moments in K-and Cr-holedoped BaFe 2 As 2 . An increase in the local moment with hole-doping is found, supporting the theoretical scenario in which a Mott insulating state that would be realized for half-filled conduction bands has an influence throughout the phase diagram of these iron-pnictides.A scenario has recently been proposed in the field of Fe-based superconductors, where the low energy physics is described in terms of a coexistence of strongly and weakly correlated electrons [1]. Such a picture provides a framework to understand a wealth of experiments on quasiparticle mass enhancements (specific heat, low-frequency optical conductivity, angleresolved photoemission spectroscopy, quantum oscillations etc.) in electron-and hole-doped A direct method to probe the local magnetic moment in transition metal compounds is Kβ coreto-core (CTC) x-ray emission spectroscopy (XES) that is sensitive to the local 3d spin because of the intra-atomic 3p-3d exchange interaction [5,6] The unoccupied density of states around Fe can be probed by means of K edge x-ray absorption spectroscopy (XAS) providing information that is complementary to Kβ spectroscopy. We have recorded high-energy resolution fluorescence detected XAS on all K-and Cr-doped samples.All samples were plate-like single crystals grown by the self-flux technique as detailed elsewhere (111) monochromator crystals. The inelastically scattered photons were analyzed using a set of five spherically bent Ge(620) crystals that were arranged with the sample and detector (avalanche photodiode) in a vertical Rowland geometry (R = 1 m). The surface of the samples was aligned to 45º with respect to the incident beam direction, i.e. the angle between the electric field of the linearly polarized x-rays and the sample [001] direction. Non-resonant Fe Kβ XES measurements were recorded at incident energy 7200 eV. High-energy resolution fluorescence-detected x-ray absorption near edge structure (HERFD-XANES) spectra were obtained by setting the emission energy to the maximum of the Kβ 1,3 line while scanning the incoming energy through the absorption edge. The resulting spectrum is an approximation to the 1s photoabsorption cross section with sharper spectral features than in standard XAS [5,6]. The total experimental broadening, determined as full width at half maximum of the elastic profiles, was 1.3 eV. All the measurements were performed at room temperature. Both XES and HERFD-XANES spectra have been normalized in area using the ranges 7025-7080 eV and 7105-7190 eV respectively.Non-resonant Fe Kβ CTC XES spectra have been measured as a function of doping in Ba 1-x K x Fe 2 As 2 (0 ≤ x ≤ 1) and Ba(Fe 1-x Cr x ) 2 As 2 (0.026 ≤ x ≤ 0.47). Figure 1( [20] where J is the exchange integral between the electrons in the 3p and 3d shells. It becomes visible in the difference spectra of Figure 1 and is about 10-...

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Angular dependence of x-ray absorption spectrum for field-aligned iron-based superconductors

Cited by 22 publications

References 15 publications

Anomalous Hall effect in the van der Waals bonded ferromagnet Fe3−xGeTe2

Anomalous Hall effect in the van der Waals bonded ferromagnet Fe3−xGeTe2

Pressure dependence of the electronic structure and spin state in Fe1.01Se superconductors probed by x-ray absorption and x-ray emission spectroscopy

Evidence of Mott physics in iron pnictides from x-ray spectroscopy

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