Experimental application of sum rules for electron energy loss magnetic chiral dichroism

Calmels, L.; Houdellier, Florent; Warot-Fonrose, Bénédicte; Gatel, Christophe; Hÿtch, Martin; Serin, V.; Snoeck, E.; Schattschneider, P.

doi:10.1103/physrevb.76.060409

Cited by 86 publications

(80 citation statements)

References 12 publications

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“…In Fig. 2a, extremely strong EMCD signals (about 33% difference for Fe and 42% for Ni) were observed [13][14]20 , which are critical for further quantitative analysis of magnetic structures. Here, we define that an EMCD signal of Fe or Ni has a 'L3 À L2 þ ' sign in case that it is negative on L 3 edge and positive on L 2 edge, while the contrary situation corresponds to a 'L3 þ L2 À ' sign.…”

Section: Resultsmentioning

confidence: 99%

“…In this work, we experimentally demonstrate how we develop the site-specific EMCD method by adjusting dynamical diffraction conditions to modulate the magnetic circular dichroism (MCD) signals at non-equivalent crystallographic sites, and further using dynamical diffraction calculations to extract the site-specific MCD spectra with quantitative site-specific magnetic structure information obtained in an example of NiFe 2 O 4 (NFO). Compared with previous EMCD works on the detection and analysis of ferromagnetic signals 13,14 , in this work we develop the sitespecific EMCD method as a unique technique, which is capable of quantitatively solving the unknown magnetic structures of the materials with non-equivalent crystallographic sites in a nanoscale level with a high site specificity. It is the first work to experimentally demonstrate that the transmitted electron source can be used to quantitatively determine magnetic structure in complex materials.…”

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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: Resultsmentioning

confidence: 99%

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confidence: 99%

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

Wang

Zhong

et al. 2013

Nat Commun

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“…By using reciprocal space maps we are able to evaluate how the apparent m L /m S ratio varies due to asymmetry and noise with (k x , k y ). The m L /m S ratio can, according to the sum rules [6,7], be calculated from:…”

Section: Reciprocal Space Mapsmentioning

confidence: 99%

“…These expressions are fundamental for the quantitative analysis of XMCD measurements. For EMCD the sum rules were derived only recently [6,7], assuming a set of approximations similar to x-ray absorption sum rules, such as taking into account only dipole transitions. In the case of L 2,3 edges of Fe the sum rules consider transitions from 2p to 3d states only.…”

Section: The Sum Rules and Evaluation Of M L /M S Ratiomentioning

confidence: 99%

Reciprocal and real space maps for EMCD experiments

et al. 2010

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Electron magnetic chiral dichroism (EMCD) is an emerging tool for quantitative measurements of magnetic properties using the transmission electron microscope (TEM), with the possibility of nanometer resolution. The geometrical conditions, data treatment and electron gun settings are found to influence the EMCD signal. In this article, particular care is taken to obtain a reliable quantitative measurement of the ratio of orbital to spin magnetic moment using energy filtered diffraction patterns. For this purpose, we describe a method for data treatment, normalization and selection of mirror axis. The experimental results are supported by theoretical simulations based on dynamical diffraction and density functional theory. Special settings of the electron gun, so called telefocus mode, enable a higher intensity of the electron beam, as well as a reduction of the influence from artifacts on the signal. Using these settings, we demonstrate the principle of acquiring real space maps of the EMCD signal. This enables advanced characterization of magnetic materials with superior spatial resolution.

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“…However, a careful examination and comparison of the scattering cross section for EELS and XAS shows that a simple, commercially available TEM equipped with a spectrometer is all that is needed to study MCD with electron scattering. [7][8][9][10][11][12] In this paper we present a review of the principles involved in EMCD experiments, together with a detailed description of the techniques used and a few illustrative examples.…”

Section: Introductionmentioning

confidence: 99%

Energy-loss magnetic chiral dichroism (EMCD): Magnetic chiral dichroism in the electron microscope

et al. 2008

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A new technique called energy-loss magnetic chiral dichroism (EMCD) has recently been developed [P. Schattschneider, et al. Nature 441, 486 (2006)] to measure magnetic circular dichroism in the transmission electron microscope (TEM) with a spatial resolution of 10 nm. This novel technique is the TEM counterpart of x-ray magnetic circular dichroism, which is widely used for the characterization of magnetic materials with synchrotron radiation. In this paper we describe several experimental methods that can be used to measure the EMCD signal [P. Schattschneider, et al. and give a review of the recent improvements of this new investigation tool. The dependence of the EMCD on several experimental conditions (such as thickness, relative orientation of beam and sample, collection and convergence angle) is investigated in the transition metals iron, cobalt, and nickel. Different scattering geometries are illustrated; their advantages and disadvantages are detailed, together with current limitations. The next realistic perspectives of this technique consist of measuring atomic specific magnetic moments, using suitable spin and orbital sum rules, [L. Calmels, et al. Phys. Rev. B 76, 060409 (2007); J. Rusz, et al. Phys. Rev. B 76, 060408 (2007)] with a resolution down to 2 to 3 nm.

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Experimental application of sum rules for electron energy loss magnetic chiral dichroism

Cited by 86 publications

References 12 publications

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

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

Reciprocal and real space maps for EMCD experiments

Energy-loss magnetic chiral dichroism (EMCD): Magnetic chiral dichroism in the electron microscope

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