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432 results on '"Meckenstock, R."'

1. Extracting the Dynamic Magnetic Contrast in Time-Resolved X-ray Transmission Microscopy

Author

Schaffers, T., Feggeler, T., Pile, S., Meckenstock, R., Buchner, M., Spoddig, D., Ney, V., Farle, M., Wende, H., Wintz, S., Weigand, M., Ohldag, H., Ollefs, K., and Ney, A.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Using a time-resolved detection scheme in scanning transmission X-ray microscopy (STXM) we measured element resolved ferromagnetic resonance (FMR) at microwave frequencies up to 10\,GHz and a spatial resolution down to 20\,nm at two different synchrotrons. We present different methods to separate the contribution of the background from the dynamic magnetic contrast based on the X-ray magnetic circular dichroism (XMCD) effect. The relative phase between the GHz microwave excitation and the X-ray pulses generated by the synchrotron, as well as the opening angle of the precession at FMR can be quantified. A detailed analysis for homogeneous and inhomogeneous magnetic excitations demonstrates that the dynamic contrast indeed behaves as the usual XMCD effect. The dynamic magnetic contrast in time-resolved STXM has the potential be a powerful tool to study the linear and non-linear magnetic excitations in magnetic micro- and nano-structures with unique spatial-temporal resolution in combination with element selectivity., Comment: 9 pages, 7 figures

Published
2019
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2. Non-standing spin-waves in confined micrometer-sized ferromagnetic structures under uniform excitation

Author

Pile, S, Feggeler, T, Schaffers, T, Meckenstock, R, Buchner, M, Spoddig, D, Zingsem, B, Ney, V, Farle, M, Wende, H, Ohldag, H, Ney, A, and Ollefs, K

Subjects
Physical Sciences, Engineering, Technology, Applied Physics
Abstract

A non-standing characteristic of directly imaged spin-waves in confined micrometer-sized ultrathin Permalloy (Ni 80 Fe 20) structures is reported along with evidence of the possibility to alter the observed state by modifications to the sample geometry. Using micromagnetic simulations, the presence of the spin-wave modes excited in the Permalloy stripes along with the quasi-uniform modes was observed. The predicted spin-waves were imaged in direct space using time resolved scanning transmission X-ray microscopy, combined with a ferromagnetic resonance excitation scheme (STXM-FMR). STXM-FMR measurements revealed a non-standing characteristic of the spin-waves. Also, it was shown by micromagnetic simulations and confirmed using STXM-FMR results that the observed characteristic of the spin-waves can be influenced by the local magnetic fields in different sample geometries.

Published
2020

4. Dipole-dipole interaction in arrays of Fe/Fe$_x$O$_y$ core/shell nanocubes probed by ferromagnetic resonance

Author

Sukhov, A., Horley, P. P., Berakdar, J., Terwey, A., Meckenstock, R., and Farle, M.

Subjects
Condensed Matter - Materials Science
Abstract

This paper represents a detailed theoretical study of the role of the longrange magnetic dipole-dipole interaction evidenced by the ferromagnetic resonance (FMR) spectra for the ordered arrays of cubic nanoparticles. We show that the size of the array essentially controls the stability of the system, allowing to suppress the intermittent low-field excitations starting from the arrays formed by 6x6 nanoparticles. Our numerical simulations allow to determine the threshold inter-particle distance (around 80 {\div} 100 nm), after which the dipole-dipole interaction becomes negligible so that the FMR spectrum of the nanoparticle arrays becomes the same as the spectrum featured by a single nanoparticle. We also compare our simulations with experimental FMR-spectra of 24 Fe/Fe$_x$O$_y$-nanocubes irregularly placed on a substrate., Comment: 16 pages, 8 figures

Published
2014
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6. Spin pumping at interfaces with ferro- and paramagnetic Fe60Al40 films acting as spin source and spin sink.

Author

Strusch, T., Lenz, K., Meckenstock, R., Bali, R., Ehrler, J., Lindner, J., Fassbender, J., Farle, M., Potzger, K., and Semisalova, A.

Subjects
MOTION picture acting, NUCLEAR spin, PHASE transitions, FERROMAGNETIC resonance, TRANSITION metal alloys, THIN films
Abstract

We present a study of spin pumping efficiency and determine the spin mixing conductance and spin diffusion length in thin bilayer films based on 3d transition metal alloy Fe60Al40. Due to its magnetostructural phase transition, Fe60Al40 can be utilized as a ferromagnetic (FM) or paramagnetic (PM) material at the same temperature depending on its structural order; thus a thin Fe60Al40 film can act as a spin source or a spin sink when interfaced with a paramagnet or a ferromagnet, respectively. Ferromagnetic resonance measurements were performed in a frequency range of 5–35 GHz on bilayer films composed of FM–Fe60Al40/Pd and PM–Fe60Al40/Ni80Fe20 (permalloy). The increase in damping with the thickness of the paramagnetic layer was interpreted as a result of spin pumping into the paramagnet. We determine the spin mixing conductance g P d ↑↓ = (3.8 ± 0.5) × 10 18 m − 2 at the FM–Fe60Al40/Pd interface and the spin diffusion length λ P d = 9.1 ± 2.0 nm in Pd. For the PM–Fe60Al40/permalloy interface, we find a spin mixing conductance g F e A l ↑↓ = (2.1 ± 0.2) × 10 18 m − 2 and a spin diffusion length λ F e A l = 11.9 ± 0.2 nm for PM–Fe60Al40. The demonstrated bi-functionality of the Fe60Al40 alloy in spin pumping structures may be promising for spintronic applications. [ABSTRACT FROM AUTHOR]

Published
2022
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8. The Asymmetric Response Concept explains ecological consequences of multiple stressor exposure and release

Author

Vos, M., Hering, D., Gessner, M.O., Leese, F., Schäfer, R.B., Tollrian, R., Boenigk, J., Haase, P., Meckenstock, R., Baikova, D., Bayat, H., Beermann, A., Beißer, D., Beszteri, B., Birk, S., Boden, L., Brauer, V., Brauns, Mario, Buchner, D., Burfeid-Castellanos, A., David, G., Deep, A., Doliwa, A., Dunthorn, M., Enß, J., Escobar-Sierra, C., Feld, C.K., Fohrer, N., Grabner, D., Hadziomerovic, U., Jähnig, S.C., Jochmann, M., Khaliq, S., Kiesel, J., Kuppels, A., Lampert, K.P., Yen Le, T.T., Lorenz, A.W., Medina Madariaga, G., Meyer, B., Pantel, J.H., Pimentel, I.M., Mayombo, N.S., Nguyen, H.H., Peters, K., Pfeifer, S.M., Prati, S., Probst, A.J., Reiner, D., Rolauffs, P., Schlenker, Alexandra, Schmidt, T.C., Shah, M., Sieber, G., Stach, T.L., Tielke, A.-K., Vermiert, A.-M., Weiss, M., Weitere, Markus, Sures, B., Vos, M., Hering, D., Gessner, M.O., Leese, F., Schäfer, R.B., Tollrian, R., Boenigk, J., Haase, P., Meckenstock, R., Baikova, D., Bayat, H., Beermann, A., Beißer, D., Beszteri, B., Birk, S., Boden, L., Brauer, V., Brauns, Mario, Buchner, D., Burfeid-Castellanos, A., David, G., Deep, A., Doliwa, A., Dunthorn, M., Enß, J., Escobar-Sierra, C., Feld, C.K., Fohrer, N., Grabner, D., Hadziomerovic, U., Jähnig, S.C., Jochmann, M., Khaliq, S., Kiesel, J., Kuppels, A., Lampert, K.P., Yen Le, T.T., Lorenz, A.W., Medina Madariaga, G., Meyer, B., Pantel, J.H., Pimentel, I.M., Mayombo, N.S., Nguyen, H.H., Peters, K., Pfeifer, S.M., Prati, S., Probst, A.J., Reiner, D., Rolauffs, P., Schlenker, Alexandra, Schmidt, T.C., Shah, M., Sieber, G., Stach, T.L., Tielke, A.-K., Vermiert, A.-M., Weiss, M., Weitere, Markus, and Sures, B.

Abstract

Our capacity to predict trajectories of ecosystem degradation and recovery is limited, especially when impairments are caused by multiple stressors. Recovery may be fast or slow and either complete or partial, sometimes result in novel ecosystem states or even fail completely. Here, we introduce the Asymmetric Response Concept (ARC) that provides a basis for exploring and predicting the pace and magnitude of ecological responses to, and release from, multiple stressors. The ARC holds that three key mechanisms govern population, community and ecosystem trajectories. Stress tolerance is the main mechanism determining responses to increasing stressor intensity, whereas dispersal and biotic interactions predominantly govern responses to the release from stressors. The shifting importance of these mechanisms creates asymmetries between the ecological trajectories that follow increasing and decreasing stressor intensities. This recognition helps to understand multiple stressor impacts and to predict which measures will restore communities that are resistant to restoration.

Published
2023

10. Wasserbeschaffenheit

Author

Grathwohl, P., Schlippenbach, U. V., Gimbel, R., Hillemeier, B., Libra, J., Meckenstock, R., Reetz, K., Schubert, H., Ternes, T., acatech - Deutsche Akademie der Technikwissenschaften, 2012, Hüttl, Reinhard F., editor, and Bens, Oliver, editor

Published
2012
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15. Adding Azathioprine to Remission‐Induction Glucocorticoids for Eosinophilic Granulomatosis With Polyangiitis (Churg‐Strauss), Microscopic Polyangiitis, or Polyarteritis Nodosa Without Poor Prognosis Factors: A Randomized, Controlled Trial

Author

Puéchal, Xavier, Pagnoux, Christian, Baron, Gabriel, Quémeneur, Thomas, Néel, Antoine, Agard, Christian, Lifermann, François, Liozon, Eric, Ruivard, Marc, Godmer, Pascal, Limal, Nicolas, Mékinian, Arsène, Papo, Thomas, Ruppert, Anne‐Marie, Bourgarit, Anne, Bienvenu, Boris, Geffray, Loïck, Saraux, Jean‐Luc, Diot, Elisabeth, Crestani, Bruno, Delbrel, Xavier, Sailler, Laurent, Cohen, Pascal, Le Guern, Véronique, Terrier, Benjamin, Groh, Matthieu, Le Jeunne, Claire, Mouthon, Luc, Ravaud, Philippe, Guillevin, Loïc, Lavigne, C., Gille, T., Le Guenno, G., Rieu, V., André, M., Goulenok, T., Federici, L., Szmania, I., Bonnotte, B., Vinzio, S., Bezanahary, H., Ly, K. H., Khouatra, C., Lega, J. C., Dunand, J. F., Hamidou, M., Ponge, T., Brihaye, B., Chauveheid, P., Dawidowicz, K., Bussone, G., Crabol, Y., Fois, E., de Menthon, M., Szwebel, T. A., Arlet, J. B., Israel‐Biet, D., Bloch‐Queyrat, C., Bachmeyer, C., Lavole, A., Wislez, M., Soria, P., Viallard, J.‐F., Landron, C., Poindron, V., Pourrat, J., Magnant, J., Kyndt, X., and Meckenstock, R.

Published
2017
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23. Spatially resolved GHz magnetization dynamics of a magnetite nano-particle chain inside a magnetotactic bacterium

Author

Feggeler, T, Feggeler, T, Meckenstock, R, Spoddig, D, Zingsem, BW, Ohldag, H, Wende, H, Farle, M, Winklhofer, M, Ollefs, KJ, Feggeler, T, Feggeler, T, Meckenstock, R, Spoddig, D, Zingsem, BW, Ohldag, H, Wende, H, Farle, M, Winklhofer, M, and Ollefs, KJ

Abstract

Understanding magnonic properties of nonperiodic magnetic nanostructures requires real-space imaging of ferromagnetic resonance modes with spatial resolution well below the optical diffraction limit and sampling rates in the 5-100 GHz range. Here, we demonstrate element-specific scanning transmission x-ray microscopy-detected ferromagnetic resonance (STXM-FMR) applied to a chain of dipolarly coupled nano-particles (40-50 nm particle size) inside a single cell of a magnetotactic bacterium Magnetospirillum magnetotacticum. The ferromagnetic resonance mode of the nano-particle chain driven at 6.748 GHz and probed with 50 nm x-ray focus size was found to have a uniform phase response but non-uniform amplitude response along the chain segments due to the superposition of dipolar coupled modes of chain segments and individual particles, in agreement with micromagnetic simulations.

Published
2021

26. Tailoring spin relaxation in thin films by tuning extrinsic relaxation channels

Author

Barsukov, I., Meckenstock, R., Lindner, J., Moller, M., Hassel, C., Posth, O., Farle, M., and Wende, H.

Subjects
Damping (Mechanics) -- Analysis, Iron alloys -- Magnetic properties, Iron alloys -- Electric properties, Magnetic resonance -- Analysis, Magnetization -- Analysis, Silicon alloys -- Magnetic properties, Silicon alloys -- Electric properties, Torque -- Measurement, Iron-silicon alloys -- Magnetic properties, Iron-silicon alloys -- Electric properties, Business, Electronics, Electronics and electrical industries
Published
2010

42. Gilbert damping in NiFeGd compounds: Ferromagnetic resonance versus time-resolved spectroscopy

Author

Salikhov, R., Alekhin, A., Parpiiev, T., Pezeril, T., (0000-0002-7177-4308) Makarov, D., Abrudan, R., Meckenstock, R., Radu, F., Farle, M., Zabel, H., Temnov, V. V., Salikhov, R., Alekhin, A., Parpiiev, T., Pezeril, T., (0000-0002-7177-4308) Makarov, D., Abrudan, R., Meckenstock, R., Radu, F., Farle, M., Zabel, H., and Temnov, V. V.

Abstract

Engineering the magnetic properties (Gilbert damping, saturation magnetization, exchange stiffness, and magnetic anisotropy) of multicomponent magnetic compounds plays a key role in fundamental magnetism and its applications. Here, we perform a systematic study of (Ni81Fe19 )100−xGdx films with x = 0%, 5%, 9%, and 13% using ferromagnetic resonance (FMR), element-specific time-resolved x-ray magnetic resonance, and femtosecond time-resolved magneto-optical pump-probe techniques. The comparative analysis of field and time domain FMR methods, with complimentary information extracted from the dynamics of high-frequency exchange magnons in ferromagnetic thin films, is used to investigate the dependence of Gilbert damping on the Gd concentration.

Published
2019

44. Toward broad-band x-ray detected ferromagnetic resonance in longitudinal geometry.

Author

Ollefs, K., Meckenstock, R., Spoddig, D., Römer, F. M., Hassel, Ch., Schöppner, Ch., Ney, V., Farle, M., and Ney, A.

Subjects
*FERROMAGNETIC resonance, *X-ray absorption, *MICROWAVE power transmission, *PHOTONS, *MAGNETIC properties, *SYNCHROTRONS, *MAGNETIC circular dichroism, *HELICITY of nuclear particles
Abstract

An ultrahigh-vacuum-compatible setup for broad-band X-ray detected ferromagnetic resonance (XFMR) in longitudinal geometry is introduced which relies on a low-power, continuous-wave excitation of the ferromagnetic sample. A simultaneous detection of the conventional ferromagnetic resonance via measuring the reflected microwave power and the XFMR signal of the X-ray absorption is possible. First experiments on the Fe and Co L3-edges of a permalloy film covered with Co nanostripes as well as the Fe and Ni K-edges of a permalloy film are presented and discussed. Two different XFMR signals are found, one of which is independent of the photon energy and therefore does not provide element-selective information. The other much weaker signal is element-selective, and the dynamic magnetic properties could be detected for Fe and Co separately. The dependence of the latter XFMR signal on the photon helicity of the synchrotron light is found to be distinct from the usual x-ray magnetic circular dichroism effect. [ABSTRACT FROM AUTHOR]

Published
2015
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