Effect of short-range magnetic ordering on electron energy-loss spectra in spinels

McComb, David W.; Craven, A. J.; Chioncel, Liviu; Lichtenstein, A. I.; Docherty, F. T.

doi:10.1103/physrevb.68.224420

Cited by 11 publications

(7 citation statements)

References 22 publications

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“…However, previous work on the L 23 edges in MgAl 2 O 4 is scarce [17,18], although the O K edge has attracted considerable attention [19][20][21]. In our work, we used the full multiple scattering method with muffin-tin potentials (encoded in FEFF8 software) [22] to simulate the Mg and Al L 23 edges in a normal spinel, an inverse spinel, and a modified structure.…”

Section: Experiments and Calculationmentioning

confidence: 98%

Electronic ionization induced atom migration in spinel MgAl2O4

Jiang

Spence

2010

Journal of Nuclear Materials

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Section: Experiments and Calculationmentioning

confidence: 98%

Electronic ionization induced atom migration in spinel MgAl2O4

Jiang

Spence

2010

Journal of Nuclear Materials

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“…However, similar calculations of the oxygen K-edge in chromite spinels showed significant discrepancies from the experimental result, both in peak position and intensity. Calculations of the oxygen K-edge of magnesium chromite using a simple antiferromagnetic ordering arrangement of chromium cations resulted in a significant improvement in the level of agreement with experiment (McComb et al, 2003). These calculations, carried out using a non-commercial simulation program, made use of the local spin density approximation (LSDA) within density functional theory (DFT).…”

Section: Introductionmentioning

confidence: 99%

“…Neutron powder diffraction investigations have detected dynamic short range magnetic order (SRO) up to 10 x T N in an analogous compound, zinc ferrite (Schiessl et al, 1996). A model in which dynamic SRO persists in chromite spinels to room temperature has been proposed (McComb et al, 2003). The short interaction time of the electron with the sample, relative to that of the comparatively slow neutron, may result in the dynamic SRO being detected to much higher temperatures in the TEM.…”

Section: Introductionmentioning

confidence: 99%

Probing magnetic order in EELS of chromite spinels using both multiple scattering (FEFF8.2) and DFT (WIEN2k)

Eustace

McComb

Craven

2010

Micron

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The electron energy loss near edge structure on the O K-edge from chromite spinels contains fine structure from the hybridisation of the O p-orbitals and the Cr d-orbitals. Unlike the aluminates, a non-spin polarised calculation of this fine structure differs significantly from experimental observations. This is due to the large magnetic moment on the Cr. Calculations using simplified collinear ordering of the spins and the local spin density approximation give much improved agreement. A real space multiple scattering formalism and a reciprocal space density functional formalism give results in substantial agreement. In general, the actual spin arrangement of these chromites is not known since they are typically frustrated magnetic systems with ordering temperatures in the 10-20K range. The calculations are based on the hypothesis that dynamic short range order persists to room temperature over the time scale of the interaction with the fast electron. However, it is possible that the observed effects are due to the strong paramagnetism present at room temperatures but which it is not possible to simulate accurately at present.

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“…Several more crucial factors, including spin order, lattice parameter and on‐site Coulomb energy, have also aroused great interest. McComb et al 20 . performed the theoretical simulations of oxygen K ‐edge of antiferromagnetic (AFM) spinel MgCr 2 O 4 above Néel temperature.…”

Section: Introductionmentioning

confidence: 99%

Several factors influencing energy‐loss near‐edge structure calculations using Wien2k

Ding

Yang

et al. 2022

Journal of Microscopy

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Electron energy‐loss spectroscopy (EELS) is widely applied combining with transmission electron microscopes with high spatial resolution, but its interpretation is a challenging task. One of the reasons is that the factors affecting EELS are very complicated. In this paper, we focus on the several factors involved in density functional theory (DFT) calculations. The sensitivity of calculated energy‐loss near‐edge structure (ELNES) to spin order, pressure and on‐site Coulomb energy U has been discussed. Since EELS technique detects the local environment of atoms, the influence of spin order cannot be ignored. The chemical shifts and peak intensity of ELNES are also closely related to corresponding pressure. The correlation effects are very important for transition metal compounds and play a key role in EELS simulations. An overview of the effects of these factors on the ELNES is presented with the help of Wien2k code. The antiferromagnetic order results in the decreasing of intensities of related peaks and the moving of the peaks to high energy loss. The decreasing of lattice parameters causes the ELNES peaks to shift to high energy loss, and the peak shifts at the higher energy loss are more significant. The increase of correlation effect leads to the ELNES peaks to shift to high energy loss accompanied by the increase of the relative intensity of the peaks which locate at higher energy loss. Our work helps to understand how these factors affect EELS and to explain and predict the experimental EELS spectra. Through the discussion of these factors, we propose that some factors could not be ignored in EELS simulations.

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Effect of short-range magnetic ordering on electron energy-loss spectra in spinels

Cited by 11 publications

References 22 publications

Electronic ionization induced atom migration in spinel MgAl2O4

Electronic ionization induced atom migration in spinel MgAl2O4

Probing magnetic order in EELS of chromite spinels using both multiple scattering (FEFF8.2) and DFT (WIEN2k)

Several factors influencing energy‐loss near‐edge structure calculations using Wien2k

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