X-ray-absorption spectroscopy at the Fe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">L</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mo>,</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>threshold in iron oxides

Crocombette, Jean-Paul; Pollak, M.; Jollet, F.; Thromat, N.; Gautier-Soyer, M.

doi:10.1103/physrevb.52.3143

Cited by 240 publications

(183 citation statements)

References 22 publications

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153

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“…showing a minimum influence of the type of R +3 . On the contrary, the XANES spectrum of LuFeCoO 4 is markedly different, and its line shape is very similar to that shown by iron oxides with formal valence Fe +3 like LaFeO 3 [54] and α-Fe 2 O 3 [55]. Besides, the XANES of LuFeCoO 4 at the Co L 2,3 edges agrees with that of compounds with formal valence Co 2+ [56].…”

Section: A Xanes At the O K Edgesupporting

confidence: 68%

Electronic states ofRFe2O4(R=Lu,Yb,Tm
Lafuerza
¹
,
García
²
,
Subı́as
³

et al. 2014
Phys. Rev. B
11
2
4
1
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We here report an investigation of the electronic states in the RFe 2 O 4 (R = Lu, Yb, Tm, Y) mixed-valence ferrites by means of soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements together with ab initio theoretical calculations. The presence of Fe +2 and Fe +3 pure ionic species is discarded in the XAS spectra at the O K edge in both experimental data and simulations based on the multiple scattering theory. Similarly, no trace of Fe +2 /Fe +3 contributions is detected in the XMCD spectra at the Fe K edge. On the other hand, the XAS and XMCD spectra at the Fe L 2,3 edges can be well described in terms of Fe +2 /Fe +3 contributions, and are also supported by multiplet calculations. This finding can be interpreted as the existence of a mixture of 3d 5 /3d 6 configurations at the Fe atoms. Alternative ferrimagnetic spin orderings based on a trimodal Fe valence distribution are also proposed and discussed. Finally, a possible explanation for the strong dependence of the Fe L 2,3 edges XMCD signal magnitude on both the sample surface preparation and detection method is presented.

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Section: A Xanes At the O K Edgesupporting

confidence: 68%

Electronic states ofRFe2O4(R=Lu,Yb,Tm
Lafuerza
¹
,
García
²
,
Subı́as
³

et al. 2014
Phys. Rev. B
11
2
4
1
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show abstract

“…, and D for t 2 structures) are close to those simulated for Cr 2 O 3 . 33 Also Fe 3+ presents octahedral symmetry, 34 in good agreement with what observed on Fe edge spectra in BFO thin films. 28 The 3+ octahedral ground state is consistent with expectation from theoretical models.…”

supporting

confidence: 85%

Unraveling the magnetic properties of BiFe_0.5Cr_0.5O₃ thin films

et al. 2015

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“…Laboratory measurements and theoretical calculations of Crocombette et al (1995) first indicated that the iron L-shell opacity of iron oxides peaks near $ 17:75 Å , which is $200 mÅ longer than what is observed in the MCG À6-30-15 spectrum. However, recent communications with that group have now revealed that there was an error in the wavelength scale in that paper (J. P. Crocombette 2000, private communication;M.…”

Section: Absorption By Dust Particlesmentioning

confidence: 96%

Can a Dusty Warm Absorber Model Reproduce the Soft X‐Ray Spectra of MCG −6‐30‐15 and Markarian 766?

Šako¹,

Kahn²,

Branduardi‐Raymont³

et al. 2003

ApJ

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XMM-Newton RGS spectra of MCG À6-30-15 and Mrk 766 exhibit complex discrete structure, which was interpreted in a paper by Branduardi-Raymont and coworkers as evidence for the existence of relativistically broadened Ly emission from carbon, nitrogen, and oxygen, produced in the innermost regions of an accretion disk around a Kerr black hole. This suggestion was subsequently criticized in a paper by Lee and coworkers, who argued that for MCG À6-30-15, the Chandra HETG spectrum, which is partially overlapping the RGS in spectral coverage, is adequately fitted by a dusty warm absorber model, with no relativistic line emission. We present a reanalysis of the original RGS data sets in terms of the model by Lee and coworkers. Specifically, we show that (1) the explicit model given by Lee and coworkers differs markedly from the RGS data, especially at longer wavelengths, beyond the region sampled by the HETG; (2) generalizations of the Lee and coworkers model, with all parameters left free, do provide qualitatively better fits to the RGS data, but are still incompatible with the detailed spectral structure; (3) the ionized oxygen absorption-line equivalent widths are well measured with the RGS for both sources, and place very tight constraints on both the column densities and turbulent velocity widths of O vii and O viii. The derived column densities are well below those posited by Lee and coworkers and are insufficient to play any role in explaining the observed edge-like feature near 17.5 Å ; (4) the lack of a significant neutral oxygen edge near 23 Å places very strong limits on any possible contribution of absorption to the observed structure by dust embedded in a warm medium; and (5) the original relativistic line model with warm absorption proposed by BranduardiRaymont and coworkers provides a superior fit to the RGS data, both in the overall shape of the spectrum and in the discrete absorption lines. We also discuss a possible theoretical interpretation for the putative relativistic Ly line emission in terms of the photoionized surface layers of the inner regions of an accretion disk. While there are still a number of outstanding theoretical questions about the viability of such a model, it is interesting to note that simple estimates of key parameters are roughly compatible with those derived from the observed spectra.

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X-ray-absorption spectroscopy at the FeL2,3threshold in iron oxides

Cited by 240 publications

References 22 publications

Electronic states ofRFe2O4(R=Lu,Yb,Tm
Lafuerza
¹
,
García
²
,
Subı́as
³

et al. 2014
Phys. Rev. B
11
2
4
1
View full text Add to dashboard Cite

Electronic states ofRFe2O4(R=Lu,Yb,Tm
Lafuerza
¹
,
García
²
,
Subı́as
³

et al. 2014
Phys. Rev. B
11
2
4
1
View full text Add to dashboard Cite

Unraveling the magnetic properties of BiFe_0.5Cr_0.5O₃ thin films

Can a Dusty Warm Absorber Model Reproduce the Soft X‐Ray Spectra of MCG −6‐30‐15 and Markarian 766?

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X-ray-absorption spectroscopy at the FeL2,3threshold in iron oxides

Cited by 240 publications

References 22 publications

Electronic states ofRFe2O4(R=Lu,Yb,TmLafuerza1, García2, Subı́as3 et al. 2014Phys. Rev. B11241View full textAdd to dashboardCite

Electronic states ofRFe2O4(R=Lu,Yb,TmLafuerza1, García2, Subı́as3 et al. 2014Phys. Rev. B11241View full textAdd to dashboardCite

Unraveling the magnetic properties of BiFe0.5Cr0.5O3 thin films

Can a Dusty Warm Absorber Model Reproduce the Soft X‐Ray Spectra of MCG −6‐30‐15 and Markarian 766?

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Product

Resources

About

Electronic states ofRFe2O4(R=Lu,Yb,Tm
Lafuerza
¹
,
García
²
,
Subı́as
³

et al. 2014
Phys. Rev. B
11
2
4
1
View full text Add to dashboard Cite

Electronic states ofRFe2O4(R=Lu,Yb,Tm
Lafuerza
¹
,
García
²
,
Subı́as
³

et al. 2014
Phys. Rev. B
11
2
4
1
View full text Add to dashboard Cite

Unraveling the magnetic properties of BiFe_0.5Cr_0.5O₃ thin films