Effect of Bloch wave electron propagation and momentum-resolved signal detection on the quantitative and site-specific electron magnetic chiral dichroism of magnetic spinel oxide thin films

Loukya, B.; Negi, Devendra Singh; Dileep, K.; Pachauri, Neha; Gupta, Arunava; Datta, Ranjan

doi:10.1103/physrevb.91.134412

Cited by 16 publications

(6 citation statements)

References 43 publications

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“…This may lead to a stronger weight of the non-magnetic component in the resulting EMCD spectra which, when combined with the already weak magnetic component, would complicate extraction. Alternatively, this may be caused by dynamical diffraction effects, such as have been studied in previous reports 31 . However, in this case, we would expect a sign inversion on both edges rather than one edge preferentially.…”

Section: Discussionmentioning

confidence: 92%

Single-pass STEM-EMCD on a zone axis using a patterned aperture: progress in experimental and data treatment methods

Thersleff

Schönström

Tai

et al. 2019

Sci Rep

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Measuring magnetic moments in ferromagnetic materials at atomic resolution is theoretically possible using the electron magnetic circular dichroism (EMCD) technique in a (scanning) transmission electron microscope ((S)TEM). However, experimental and data processing hurdles currently hamper the realization of this goal. Experimentally, the sample must be tilted to a zone-axis orientation, yielding a complex distribution of magnetic scattering intensity, and the same sample region must be scanned multiple times with sub-atomic spatial registration necessary at each pass. Furthermore, the weak nature of the EMCD signal requires advanced data processing techniques to reliably detect and quantify the result. In this manuscript, we detail our experimental and data processing progress towards achieving single-pass zone-axis EMCD using a patterned aperture. First, we provide a comprehensive data acquisition and analysis strategy for this and other EMCD experiments that should scale down to atomic resolution experiments. Second, we demonstrate that, at low spatial resolution, promising EMCD candidate signals can be extracted, and that these are sensitive to both crystallographic orientation and momentum transfer.

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Section: Discussionmentioning

confidence: 92%

Single-pass STEM-EMCD on a zone axis using a patterned aperture: progress in experimental and data treatment methods

Thersleff

Schönström

Tai

et al. 2019

Sci Rep

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“…Whereas, in the Fourier method, the object function is expanded into various frequencies of plane waves with no information on the scattering angle. Both the scattering processes involve the presence of various frequency components of the outgoing waves that are reminiscent of the picture of Bloch wave propagation of probe electrons in a periodic crystal but with a discrete range of frequencies having symmetry with the crystal periodicity [39] For atomic systems, the electrostatic potential replaces the slit object function. The FT of isolated and periodic atomic potential in the diffraction plane is the atom scattering factor ( ) f k and structure factor ( ) F g , respectively.…”

Section: Methods Based On Fresnel-huygens Construction and Fourier Tr...mentioning

confidence: 99%

Direct methods applied to phase retrieval in high resolution transmission electron microscopy

Bhat

Datta

2022

J. Phys. Commun.

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An alternative reconstruction method is proposed for retrieving the object exit wave function (OEW) directly from the recorded image intensity pattern in high resolution transmission electron microscopy (HRTEM). The method is based on applying a modified intensity equation representing the HRTEM image. A comparative discussion is provided between the existing methodologies involved in the reconstruction of OEW, off-axis electron holography and the present proposal. Phase shift extracted from the experimental images of MoS2, BN and ZnO are found to be in excellent agreement for most of the atom types investigated with the theoretical reference values. Additionally, it is shown that the Fourier series expansion of diffraction pattern is effective in retrieving the isolated and periodic image functions of certain forms directly. However, for aperiodic object information e.g., defects, dopants, edges etc., the first method works in entirety.

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“…Therefore, it is necessary to image their specific distributions in a sub-ångstrom resolution. Among the techniques for detecting the distributions and the preferred site of the doping ions [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ], aberration-corrected transmission electron microscopy (Cs-corrected TEM) and scanning transmission electron microscopy (Cs-corrected STEM) equipped with energy-dispersive X-ray analysis (EDX) have recently made significant progress in space and time resolution. These techniques achieve a surprisingly high spatial resolution below 0.5 Å and readily realize a direct imaging and electronic-state detection of individual atoms and even chemical bonds.…”

Section: Introductionmentioning

confidence: 99%

The Cation Distributions of Zn-doped Normal Spinel MgFe2O4 Ferrite and Its Magnetic Properties

Zeng

Hou

et al. 2022

Materials

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Determining the exact occupation sites of the doping ions in spinel ferrites is vital for tailoring and improving their magnetic properties. In this study, the distribution and occupation sites of cations in MgFe2O4 and Zn-doped MgFe2O4 ferrite are imaged by Cs-STEM. The experimental STEM images along [001], [011] and [111] orientations suggest that the divalent Mg2+ cations occupy all A sites, and the trivalent Fe3+ cations occupy all B sites in MgFe2O4 ferrite prepared by electrospinning, which is consistent with the normal spinel structure. We further clarify that the preferred sites of dopant Zn2+ ions are Fe3+ crystallographic sites in the Zn-doped MgFe2O4 ferrite nanofibers. Magnetic measurements show that Zn doping affects the spin states of the Fe3+, and the Fe3+-O2−-Fe3+ super-exchange interaction leads to enhancements in the magnetization and reduction in the Curie temperature. Our work should contribute a significant step toward eventually realizing the practical application of doped spinel ferrites.

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Effect of Bloch wave electron propagation and momentum-resolved signal detection on the quantitative and site-specific electron magnetic chiral dichroism of magnetic spinel oxide thin films

Cited by 16 publications

References 43 publications

Single-pass STEM-EMCD on a zone axis using a patterned aperture: progress in experimental and data treatment methods

Single-pass STEM-EMCD on a zone axis using a patterned aperture: progress in experimental and data treatment methods

Direct methods applied to phase retrieval in high resolution transmission electron microscopy

The Cation Distributions of Zn-doped Normal Spinel MgFe2O4 Ferrite and Its Magnetic Properties

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