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Zeiger, Paul
Publications (4 of 4) Show all publications
Zeiger, P. & Rusz, J. (2020). Efficient and Versatile Model for Vibrational STEM-EELS. Physical Review Letters, 124(2), Article ID 025501.
Open this publication in new window or tab >>Efficient and Versatile Model for Vibrational STEM-EELS
2020 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 124, no 2, article id 025501Article in journal (Refereed) Published
Abstract [en]

We introduce a novel method for the simulation of the impact scattering in vibrational scanning transmission electron microscopy electron energy loss spectroscopy simulations. The phonon-loss process is modeled by a combination of molecular dynamics and elastic multislice calculations within a modified frozen phonon approximation. The key idea is thereby to use a so-called S thermostat in the classical molecular dynamics simulation to generate frequency dependent configurations of the vibrating specimen's atomic structure. The method includes correlated motion of atoms and provides vibrational spectrum images at a cost comparable to standard frozen phonon calculations. We demonstrate good agreement of our method with simulations and experiments for a 15 nm flake of hexagonal boron nitride.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2020
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-404696 (URN)10.1103/PhysRevLett.124.025501 (DOI)000506852200008 ()32004041 (PubMedID)
Funder
Swedish Research CouncilSwedish National Infrastructure for Computing (SNIC)
Available from: 2020-02-25 Created: 2020-02-25 Last updated: 2020-02-25Bibliographically approved
Negi, D. S., Zeiger, P., Jones, L., Idrobo, J.-C., van Aken, P. A. & Rusz, J. (2019). Prospect for detecting magnetism of a single impurity atom using electron magnetic chiral dichroism. Physical Review B, 100(10), Article ID 104434.
Open this publication in new window or tab >>Prospect for detecting magnetism of a single impurity atom using electron magnetic chiral dichroism
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2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 100, no 10, article id 104434Article in journal (Refereed) Published
Abstract [en]

Dopants, even single atoms, can influence the electrical and magnetic properties of materials. Here we demonstrate the opportunity for detecting the magnetic response of an embedded magnetic impurity in a nonmagnetic host material. We combine a depth sectioning approach with electron magnetic circular dichroism in scanning transmission electron microscopy to compute the depth-resolved magnetic inelastic-scattering cross section of single Co impurity buried in the host crystal of GaAs. Our calculations suggest that the magnetic dichroic signal intensity is sensitive to the depth and lateral position of the electron probe relative to the magnetic impurity. Additionally, a more precise dichroic signal localization can be achieved via choosing higher-collection-angle (beta) apertures. Quantitative evaluation of the inelastic-scattering cross section and signal-to-noise ratio indicates that the magnetic signal from a single Co atom is on the verge of being detectable with today's state-of-the-art instrumentation.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-395834 (URN)10.1103/PhysRevB.100.104434 (DOI)000488252600004 ()
Funder
Swedish Research Council, 2017-04026Swedish National Infrastructure for Computing (SNIC)EU, Horizon 2020, 823717 ESTEEM3Göran Gustafsson Foundation for Research in Natural Sciences and Medicine
Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-25Bibliographically approved
Pohl, D., Schneider, S., Zeiger, P., Rusz, J., Tiemeijer, P., Lazar, S., . . . Rellinghaus, B. (2017). Atom size electron vortex beams with selectable orbital angular momentum. Scientific Reports, 7, Article ID 934.
Open this publication in new window or tab >>Atom size electron vortex beams with selectable orbital angular momentum
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 934Article in journal (Refereed) Published
Abstract [en]

The decreasing size of modern functional magnetic materials and devices cause a steadily increasing demand for high resolution quantitative magnetic characterization. Transmission electron microscopy (TEM) based measurements of the electron energy-loss magnetic chiral dichroism (EMCD) may serve as the needed experimental tool. To this end, we present a reliable and robust electron-optical setup that generates and controls user-selectable single state electron vortex beams with defined orbital angular momenta. Our set-up is based on a standard high-resolution scanning TEM with probe aberration corrector, to which we added a vortex generating fork aperture and a miniaturized aperture for vortex selection. We demonstrate that atom size probes can be formed from these electron vortices and that they can be used for atomic resolution structural and spectroscopic imaging - both of which are prerequisites for future atomic EMCD investigations.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2017
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-322175 (URN)10.1038/s41598-017-01077-9 (DOI)000399534800002 ()28424470 (PubMedID)
Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2017-05-17Bibliographically approved
Löfgren, A., Zeiger, P., Kocevski, V. & Rusz, J. (2016). Influence of nuclear quantum effects on frozen phonon simulations of electron vortex beam HAADF-STEM images.. Ultramicroscopy, 164, 62-69
Open this publication in new window or tab >>Influence of nuclear quantum effects on frozen phonon simulations of electron vortex beam HAADF-STEM images.
2016 (English)In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 164, p. 62-69Article in journal (Refereed) Published
Abstract [en]

We have evaluated atomic resolution high-angle annular dark field images with ordinary beams and electron vortex beams for thin crystals of bcc iron, explicitly considering the atomic vibrations using molecular dynamics. The shape of the image representing an atomic column depends on the orbital angular momentum, sample thickness and temperature. For electron vortex beams we observe characteristic doughnut-shaped images of atomic columns. It is shown how the thermal diffuse scattering reduces the depth of their central minima, which get further smeared by finite source size effects. In addition, it is shown that in calculations of HAADF-STEM images at low temperatures one has to explicitly consider the nuclear quantum effects (zero point vibrations), otherwise the effect of atomic vibrations is strongly underestimated.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-283343 (URN)10.1016/j.ultramic.2016.01.007 (DOI)000373526200008 ()26852870 (PubMedID)
Funder
Swedish Research CouncilThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
Available from: 2016-04-12 Created: 2016-04-12 Last updated: 2017-11-30Bibliographically approved
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