Magnetic order in - nanoparticles: a XMCD study

Brice-Profeta, S.; Arrio, Marie‐Anne; Tronc, E.; Menguy, Nicolas; Letard, I.; Moulin, Christophe; Noguès, M.; Chanéac, Corinne; Jolivet, Jean‐Pierre; Sainctavit, Philippe

doi:10.1016/j.jmmm.2004.09.120

Cited by 179 publications

(185 citation statements)

References 30 publications

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“…Even if at the beginning we knew nothing about the magnetic structure of NFO, the sitespecific MCD spectra can give a clear demonstration of the ferrimagnetic structure of NFO, as the coefficients a and b are just calculated out using the knowledge of crystallographic structure information and dynamical diffraction condition. The general features of site-specific EMCD spectra are consistent with the previous simulated MCD spectra of oct Fe and tet Fe via multiplet calculations 24,25 . A possible energy shift of 0.4 eV between EMCD peaks of oct Fe and tet Fe in Fig.…”

Section: Articlesupporting

confidence: 87%

“…S7 and Supplementary Methods). As a comparison, the site-specific MCD spectra cannot be experimentally obtained from X-ray magnetic circular dichroism (XMCD) except by simulating the spectra via multiplet calculations 24 . Even if at the beginning we knew nothing about the magnetic structure of NFO, the sitespecific MCD spectra can give a clear demonstration of the ferrimagnetic structure of NFO, as the coefficients a and b are just calculated out using the knowledge of crystallographic structure information and dynamical diffraction condition.…”

Section: Articlementioning

confidence: 99%

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Quantitative experimental determination of site-specific magnetic structures by transmitted electrons

Wang

Zhong

et al. 2013

Nat Commun

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Understanding the magnetic structure of materials on a nanometre scale provides fundamental information in the development of novel applications. Here we show a site-specific electron energy-loss magnetic chiral dichroism method, first experimentally demonstrating that the use of transmitted electrons allows us to quantitatively determine atomic sitespecific magnetic structure information on a nanometre scale. From one NiFe 2 O 4 nanograin in composite films, we extract its atomic site-specific magnetic circular dichroism spectra and achieve the quantitative magnetic structure information, such as site-specific total magnetic moments and orbital to spin magnetic moment ratios, by constructively selecting the specific dynamical diffraction conditions in electron energy-loss magnetic chiral dichroism experiments. The site-specific electron energy-loss magnetic chiral dichroism method shows its unique ability for solving the site-specific magnetic structure at nanoscale resolution, compared with X-ray magnetic circular dichroism and neutron diffraction. This work opens a door to meet the challenge of exploring the magnetic structures of magnetic materials at the nanoscale using transmitted electrons.

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Section: Articlesupporting

confidence: 87%

Section: Articlementioning

confidence: 99%

Quantitative experimental determination of site-specific magnetic structures by transmitted electrons

Wang

Zhong

et al. 2013

Nat Commun

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“…[13][14][15] Examining the Fe L 3 XMCD spectra for these nanoparticles (shown in the bottom panel of Fig. 2), the shape of the Fe XMCD spectra initially starts out with a mix of tetrahedral and octahedral coordination as one would except of Fe 3 O 4 .…”

Section: Resultsmentioning

confidence: 99%

“…2), the shape of the Fe XMCD spectra initially starts out with a mix of tetrahedral and octahedral coordination as one would except of Fe 3 O 4 . [13][14][15] As the Ga percentage increases the central peak quickly reduces in prominence. As has been noted, [13][14][15] the intensity of this central peak is representative of the tetrahedral coordination, so the reduction of this peak is evidence of increasing octahedral coordination of Fe as opposed to the 1/3 tetrahedral to 2/3 octahedral mix of Fe 3 O 4 .…”

Section: Resultsmentioning

confidence: 99%

“…[13][14][15] As the Ga percentage increases the central peak quickly reduces in prominence. As has been noted, [13][14][15] the intensity of this central peak is representative of the tetrahedral coordination, so the reduction of this peak is evidence of increasing octahedral coordination of Fe as opposed to the 1/3 tetrahedral to 2/3 octahedral mix of Fe 3 O 4 . In addition, comparing the relative intensities of the two downward peaks in the XMCD spectra, the lower energy peak is becoming more prominent as the concentration increases from 5% Ga to 25% gallium, which also indicates that the octahedral Fe 2þ is becoming more dominant in the spectra at higher concentrations.…”

Section: Resultsmentioning

confidence: 99%

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Enhanced magnetism of Fe3O4 nanoparticles with Ga doping

Pool¹,

Klem²,

Chorney³

et al. 2011

Journal of Applied Physics

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Magnetic (Ga x Fe 1Àx ) 3 O 4 nanoparticles with 5%-33% gallium doping (x ¼ 0.05-0.33) were measured using x-ray absorption spectroscopy and x-ray magnetic circular dichroism to determine that the Ga dopant is substituting for Fe 3þ as Ga 3þ in the tetrahedral A-site of the spinel structure, resulting in an overall increase in the total moment of the material. Frequency-dependent alternating-current magnetic susceptibility measurements showed these particles to be weakly interacting with a reduction of the cubic anisotropy energy term with Ga concentration. The element-specific dichroism spectra show that the average Fe moment is observed to increase with Ga concentration, a result consistent with the replacement of A-site Fe by Ga.

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