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2018


Learning 3D Shape Completion under Weak Supervision
Learning 3D Shape Completion under Weak Supervision

Stutz, D., Geiger, A.

Arxiv, May 2018 (article)

Abstract
We address the problem of 3D shape completion from sparse and noisy point clouds, a fundamental problem in computer vision and robotics. Recent approaches are either data-driven or learning-based: Data-driven approaches rely on a shape model whose parameters are optimized to fit the observations; Learning-based approaches, in contrast, avoid the expensive optimization step by learning to directly predict complete shapes from incomplete observations in a fully-supervised setting. However, full supervision is often not available in practice. In this work, we propose a weakly-supervised learning-based approach to 3D shape completion which neither requires slow optimization nor direct supervision. While we also learn a shape prior on synthetic data, we amortize, i.e., learn, maximum likelihood fitting using deep neural networks resulting in efficient shape completion without sacrificing accuracy. On synthetic benchmarks based on ShapeNet and ModelNet as well as on real robotics data from KITTI and Kinect, we demonstrate that the proposed amortized maximum likelihood approach is able to compete with fully supervised baselines and outperforms data-driven approaches, while requiring less supervision and being significantly faster.

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PDF Project Page Project Page [BibTex]


{Direct observation of Zhang-Li torque expansion of magnetic droplet solitons}
Direct observation of Zhang-Li torque expansion of magnetic droplet solitons

Chung, S., Tuan Le, Q., Ahlberg, M., Awad, A. A., Weigand, M., Bykova, I., Khymyn, R., Dvornik, M., Mazraati, H., Houshang, A., Jiang, S., Nguyen, T. N. A., Goering, E., Schütz, G., Gräfe, J., \AAkerman, J.

{Physical Review Letters}, 120(21), American Physical Society, Woodbury, N.Y., 2018 (article)

Abstract
Magnetic droplets are nontopological dynamical solitons that can be nucleated in nanocontact based spin torque nano-oscillators (STNOs) with perpendicular magnetic anisotropy free layers. While theory predicts that the droplet should be of the same size as the nanocontact, its inherent drift instability has thwarted attempts at observing it directly using microscopy techniques. Here, we demonstrate highly stable magnetic droplets in all-perpendicular STNOs and present the first detailed droplet images using scanning transmission X-ray microscopy. In contrast to theoretical predictions, we find that the droplet diameter is about twice as large as the nanocontact. By extending the original droplet theory to properly account for the lateral current spread underneath the nanocontact, we show that the large discrepancy primarily arises from current-in-plane Zhang-Li torque adding an outward pressure on the droplet perimeter. Electrical measurements on droplets nucleated using a reversed current in the antiparallel state corroborate this picture.

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DOI [BibTex]

DOI [BibTex]


{Transmission x-ray microscopy at low temperatures: Irregular supercurrent flow at small length scales}
Transmission x-ray microscopy at low temperatures: Irregular supercurrent flow at small length scales

Simmendinger, J., Ruoss, S., Stahl, C., Weigand, M., Gräfe, J., Schütz, G., Albrecht, J.

{Physical Review B}, 97(13), American Physical Society, Woodbury, NY, 2018 (article)

Abstract
Scanning transmission x-ray microscopy has been used to image electric currents in superconducting films at temperatures down to 20 K. We detect significant deviations from a regular current path driven by macroscopic geometrical constraints. The magnetic stray field of supercurrents in a thin YBaCuO film is mapped into a soft-magnetic coating of permalloy. The so-created local magnetization of the ferromagnetic film can be detected by dichroic absorption of polarized x rays. To enable high-quality measurements in transmission geometry, the whole heterostructure of ferromagnet, superconductor, and single-crystalline substrate has been thinned to an overall thickness of less than 1 µm. With this technique, local supercurrents can be analyzed in a wide range of temperatures and magnetic fields. The less than 100 nm spatial resolution of the magnetic signal together with simultaneously obtained nanostructural data allow the correlation of local supercurrents with the micro- and nanostructure of the superconducting film.

mms

DOI [BibTex]

DOI [BibTex]


Augmented Reality Meets Computer Vision: Efficient Data Generation for Urban Driving Scenes
Augmented Reality Meets Computer Vision: Efficient Data Generation for Urban Driving Scenes

Alhaija, H., Mustikovela, S., Mescheder, L., Geiger, A., Rother, C.

International Journal of Computer Vision (IJCV), 2018, 2018 (article)

Abstract
The success of deep learning in computer vision is based on the availability of large annotated datasets. To lower the need for hand labeled images, virtually rendered 3D worlds have recently gained popularity. Unfortunately, creating realistic 3D content is challenging on its own and requires significant human effort. In this work, we propose an alternative paradigm which combines real and synthetic data for learning semantic instance segmentation and object detection models. Exploiting the fact that not all aspects of the scene are equally important for this task, we propose to augment real-world imagery with virtual objects of the target category. Capturing real-world images at large scale is easy and cheap, and directly provides real background appearances without the need for creating complex 3D models of the environment. We present an efficient procedure to augment these images with virtual objects. In contrast to modeling complete 3D environments, our data augmentation approach requires only a few user interactions in combination with 3D models of the target object category. Leveraging our approach, we introduce a novel dataset of augmented urban driving scenes with 360 degree images that are used as environment maps to create realistic lighting and reflections on rendered objects. We analyze the significance of realistic object placement by comparing manual placement by humans to automatic methods based on semantic scene analysis. This allows us to create composite images which exhibit both realistic background appearance as well as a large number of complex object arrangements. Through an extensive set of experiments, we conclude the right set of parameters to produce augmented data which can maximally enhance the performance of instance segmentation models. Further, we demonstrate the utility of the proposed approach on training standard deep models for semantic instance segmentation and object detection of cars in outdoor driving scenarios. We test the models trained on our augmented data on the KITTI 2015 dataset, which we have annotated with pixel-accurate ground truth, and on the Cityscapes dataset. Our experiments demonstrate that the models trained on augmented imagery generalize better than those trained on fully synthetic data or models trained on limited amounts of annotated real data.

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pdf Project Page [BibTex]

pdf Project Page [BibTex]


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Assessment methodology of promising porous materials for near ambient temperature hydrogen storage applications

Minuto, F. D., Balderas-Xicohténcatl, R., Policicchio, A., Hirscher, M., Agostino, R. G.

{International Journal of Hydrogen Energy}, 43(31):14550-14556, Elsevier, Amsterdam, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Incorporation of Terbium into a Microalga Leads to Magnetotactic Swimmers

Santomauro, G., Singh, A., Park, B. W., Mohammadrahimi, M., Erkoc, P., Goering, E., Schütz, G., Sitti, M., Bill, J.

Advanced Biosystems, 2(12):1800039, 2018 (article)

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[BibTex]

[BibTex]


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Thermodynamics, kinetics and selectivity of H2 and D2 on zeolite 5A below 77K

Xiong, R., Balderas-Xicohténcatl, R., Zhang, L., Li, P., Yao, Y., Sang, G., Chen, C., Tang, T., Luo, D., Hirscher, M.

{Microporous and Mesoporous Materials}, 264, pages: 22-27, Elsevier, Amsterdam, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Volumetric hydrogen storage capacity in metal-organic frameworks

Balderas-Xicohténcatl, R., Schlichtenmayer, M., Hirscher, M.

{Energy Technology}, 6(3):578-582, Wiley-VCH, Weinheim, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


Learning 3D Shape Completion under Weak Supervision
Learning 3D Shape Completion under Weak Supervision

Stutz, D., Geiger, A.

International Journal of Computer Vision (IJCV), 2018, 2018 (article)

Abstract
We address the problem of 3D shape completion from sparse and noisy point clouds, a fundamental problem in computer vision and robotics. Recent approaches are either data-driven or learning-based: Data-driven approaches rely on a shape model whose parameters are optimized to fit the observations; Learning-based approaches, in contrast, avoid the expensive optimization step by learning to directly predict complete shapes from incomplete observations in a fully-supervised setting. However, full supervision is often not available in practice. In this work, we propose a weakly-supervised learning-based approach to 3D shape completion which neither requires slow optimization nor direct supervision. While we also learn a shape prior on synthetic data, we amortize, i.e., learn, maximum likelihood fitting using deep neural networks resulting in efficient shape completion without sacrificing accuracy. On synthetic benchmarks based on ShapeNet and ModelNet as well as on real robotics data from KITTI and Kinect, we demonstrate that the proposed amortized maximum likelihood approach is able to compete with a fully supervised baseline and outperforms the data-driven approach of Engelmann et al., while requiring less supervision and being significantly faster.

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pdf Project Page [BibTex]

pdf Project Page [BibTex]


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3D nanoprinted plastic kinoform x-ray optics

Sanli, U. T., Ceylan, H., Bykova, I., Weigand, M., Sitti, M., Schütz, G., Keskinbora, K.

{Advanced Materials}, 30(36), Wiley-VCH, Weinheim, 2018 (article)

mms pi

DOI [BibTex]

DOI [BibTex]


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High volumetric hydrogen storage capacity using interpenetrated metal-organic frameworks

Balderas-Xicohténcatl, R., Schmieder, P., Denysenko, D., Volkmer, D., Hirscher, M.

{Energy Technology}, 6(3):510-512, Wiley-VCH, Weinheim, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


Object Scene Flow
Object Scene Flow

Menze, M., Heipke, C., Geiger, A.

ISPRS Journal of Photogrammetry and Remote Sensing, 2018 (article)

Abstract
This work investigates the estimation of dense three-dimensional motion fields, commonly referred to as scene flow. While great progress has been made in recent years, large displacements and adverse imaging conditions as observed in natural outdoor environments are still very challenging for current approaches to reconstruction and motion estimation. In this paper, we propose a unified random field model which reasons jointly about 3D scene flow as well as the location, shape and motion of vehicles in the observed scene. We formulate the problem as the task of decomposing the scene into a small number of rigidly moving objects sharing the same motion parameters. Thus, our formulation effectively introduces long-range spatial dependencies which commonly employed local rigidity priors are lacking. Our inference algorithm then estimates the association of image segments and object hypotheses together with their three-dimensional shape and motion. We demonstrate the potential of the proposed approach by introducing a novel challenging scene flow benchmark which allows for a thorough comparison of the proposed scene flow approach with respect to various baseline models. In contrast to previous benchmarks, our evaluation is the first to provide stereo and optical flow ground truth for dynamic real-world urban scenes at large scale. Our experiments reveal that rigid motion segmentation can be utilized as an effective regularizer for the scene flow problem, improving upon existing two-frame scene flow methods. At the same time, our method yields plausible object segmentations without requiring an explicitly trained recognition model for a specific object class.

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Project Page [BibTex]

Project Page [BibTex]


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Thick permalloy films for the imaging of spin texture dynamics in perpendicularly magnetized systems

Finizio, S., Wintz, S., Bracher, D., Kirk, E., Semisalova, A. S., Förster, J., Zeissler, K., We\ssels, T., Weigand, M., Lenz, K., Kleibert, A., Raabe, J.

{Physical Review B}, 98(10), American Physical Society, Woodbury, NY, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Dynamic Janus metasurfaces in the visible spectral region

Yu, P., Li, J., Zhang, S., Jin, Z., Schütz, G., Qiu, C., Hirscher, M., Liu, N.

{Nano Letters}, 18(7):4584-4589, American Chemical Society, Washington, DC, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Review of ultrafast demagnetization after femtosecond laser pulses: A complex interaction of light with quantum matter

Fähnle, M., Haag, M., Illg, C., Müller, B. Y., Weng, W., Tsatsoulis, T., Huang, H., Briones Paz, J. Z., Teeny, N., Zhang, L., Kuhn, T.

{American Journal of Modern Physics}, 7(2):68-74, Science Publishing Group, New York, NY, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Current-induced skyrmion generation through morphological thermal transitions in chiral ferromagnetic heterostructures

Lemesh, I., Litzius, K., Böttcher, M., Bassirian, P., Kerber, N., Heinze, D., Zázvorka, J., Büttner, F., Caretta, L., Mann, M., Weigand, M., Finizio, S., Raabe, J., Im, M., Stoll, H., Schütz, G., Dupé, B., Kläui, M., Beach, G. S. D.

{Advanced Materials}, 30(49), Wiley-VCH, Weinheim, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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3d nanofabrication of high-resolution multilayer Fresnel zone plates

Sanli, U. T., Jiao, C., Baluktsian, M., Grévent, C., Hahn, K., Wang, Y., Srot, V., Richter, G., Bykova, I., Weigand, M., Schütz, G., Keskinbora, K.

{Advanced Science}, 5(9), Wiley-VCH, Weinheim, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Photocatalytic CO2 reduction by Cr-substituted Ba2(In2-xCrx)O5\mbox⋅(H2O)δ(0.04 ≤x ≤0.60)

Yoon, S., Gaul, M., Sharma, S., Son, K., Hagemann, H., Ziegenbalg, D., Schwingenschlogl, U., Widenmeyer, M., Weidenkaff, A.

{Solid State Sciences}, 78, pages: 22-29, Elsevier Masson SAS, Paris, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Ferromagnetism in nitrogen and fluorine substituted BaTiO3

Yoon, S., Son, K., Ebbinghaus, S. G., Widenmeyer, M., Weidenkaff, A.

{Journal of Alloys and Compounds}, 749, pages: 628-633, Elsevier B.V., Lausanne, Switzerland, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Correction of axial position uncertainty and systematic detector errors in ptychographic diffraction imaging

Loetgering, L., Rose, M., Keskinbora, K., Baluktsian, M., Dogan, G., Sanli, U., Bykova, I., Weigand, M., Schütz, G., Wilhein, T.

{Optical Engineering}, 57(8), The Society, Redondo Beach, Calif., 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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The role of surface oxides on hydrogen sorption kinetics in titanium thin films

Hadjixenophontos, E., Michalek, L., Roussel, M., Hirscher, M., Schmitz, G.

{Applied Surface Science}, 441, pages: 324-330, Elsevier B.V., Amsterdam, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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New concepts for 3d optics in x-ray microscopy

Sanli, U., Ceylan, H., Jiao, C., Baluktsian, M., Grevent, C., Hahn, K., Wang, Y., Srot, V., Richter, G., Bykova, I., Weigand, M., Sitti, M., Schütz, G., Keskinbora, K.

{Microscopy and Microanalysis}, 24(Suppl 2):288-289, Cambridge University Press, New York, NY, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Spin-wave interference in magnetic vortex stacks

Behncke, C., Adolff, C. F., Lenzing, N., Hänze, M., Schulte, B., Weigand, M., Schütz, G., Meier, G.

{Communications Physics}, 1, Nature Publishing Group, London, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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High-throughput synthesis of modified Fresnel zone plate arrays via ion beam lithography

Keskinbora, K., Sanli, U. T., Baluktsian, M., Grévent, C., Weigand, M., Schütz, G.

{Beilstein Journal of Nanotechnology}, 9, pages: 2049-2056, Beilstein-Institut, Frankfurt am Main, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Deterministic creation and deletion of a single magnetic skyrmion observed by direct time-resolved X-ray microscopy

Woo, S., Song, K. M., Zhang, X., Ezawa, M., Zhou, Y., Liu, X., Weigand, M., Finizio, S., Raabe, J., Park, M.-C., Lee, K.-Y., Choi, J. W., Min, B.-C., Koo, H. C., Chang, J.

{Nature Electronics}, 1(5):288-296, Springer Nature, London, 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic skyrmion as a nonlinear resistive element: A potential building block for reservoir computing

Prychynenko, D., Sitte, M., Litzius, K., Krüger, B., Bourianoff, G., Kläui, M., Sinova, J., Everschor-Sitte, K.

{Physical Review Applied}, 9(1), American Physical Society, College Park, Md. [u.a.], 2018 (article)

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DOI [BibTex]

DOI [BibTex]


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Tunable geometrical frustration in magnoic vortex crystals

Behncke, C., Adolff, C. F., Wintz, S., Hänze, M., Schulte, B., Weigand, M., Finizio, S., Raabe, J., Meier, G.

{Scientific Reports}, 8, Nature Publishing Group, London, UK, 2018 (article)

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DOI [BibTex]

DOI [BibTex]

2016


{Coercivity scaling in antidot lattices in Fe, Ni, and NiFe thin films}
Coercivity scaling in antidot lattices in Fe, Ni, and NiFe thin films

Gräfe, J., Schütz, G., Goering, E. J.

{Journal of Magnetism and Magnetic Materials}, 419, pages: 517-520, North-Holland, Amsterdam, 2016 (article)

Abstract
Antidot lattices can be used to artificially engineer magnetic properties in thin films, however, a conclusive model that describes the coercivity enhancement in this class of magnetic nano-structures has so far not been found. We prepared Fe, Ni, and NiFe thin films and patterned each with 21 square antidot lattices with different geometric parameters and measured their hysteretic behavior. On the basis of this extensive dataset we are able to provide a model that can describe both the coercivity scaling over a wide range of geometric lattice parameters and the influence of different materials.

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DOI Project Page [BibTex]

2016


DOI Project Page [BibTex]


Probabilistic Duality for Parallel Gibbs Sampling without Graph Coloring
Probabilistic Duality for Parallel Gibbs Sampling without Graph Coloring

Mescheder, L., Nowozin, S., Geiger, A.

Arxiv, 2016 (article)

Abstract
We present a new notion of probabilistic duality for random variables involving mixture distributions. Using this notion, we show how to implement a highly-parallelizable Gibbs sampler for weakly coupled discrete pairwise graphical models with strictly positive factors that requires almost no preprocessing and is easy to implement. Moreover, we show how our method can be combined with blocking to improve mixing. Even though our method leads to inferior mixing times compared to a sequential Gibbs sampler, we argue that our method is still very useful for large dynamic networks, where factors are added and removed on a continuous basis, as it is hard to maintain a graph coloring in this setup. Similarly, our method is useful for parallelizing Gibbs sampling in graphical models that do not allow for graph colorings with a small number of colors such as densely connected graphs.

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pdf [BibTex]


γ‐Conicein und Coniin aus Geflecktem Schierling
γ‐Conicein und Coniin aus Geflecktem Schierling

Puidokait, M., Graefe, J., Sehl, A., Steinke, K., Siehl, H., Zeller, K., Sicker, D., Berger, S.

Chemie in unserer Zeit, 50(6):382-391, 2016 (article)

Abstract
Sokrates ist das bekannteste Opfer eines 399 v.d.Z. in Athen mit dem Schierlingsbecher vollstreckten Todesurteils. Tödlich giftig wirkten darin Alkaloide wie γ‐Conicein und Coniin, die nach Mäuseurin riechen. Schaudern macht, dass dieses Gift sein Opfer allmählich bei vollem Bewusstsein lähmt und dass es kein Gegengift gibt. Auch für Tiere auf der Weide ist Gefleckter Schierling stark giftig. Daher verdrängt die Landwirtschaft den Schierling. Coniin war das erste synthetisierte Alkaloid (Ladenburg, 1886). Schierlingsgifte werden heute nicht medizinisch angewendet. Wir beschreiben die Isolierung von γ‐Conicein und Coniin aus angebautem und wildem Gefleckten Schierling und analysieren ihre Struktur spektroskopisch. Dieser Artikel gehört zur Reihe über die Isolierung und Spektroskopie von Naturstoffen und ergänzt die Kapitel des Buchs “Classics in Spectroscopy” von S. Berger und D. Sicker (Wiley‐VCH 2009). Er beruht auf studentischen Arbeiten ebenso wie auf unserem präparativen Engagement als sie betreuende Wissenschaftler.

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DOI [BibTex]

DOI [BibTex]


{Geometric control of the magnetization reversal in antidot lattices with perpendicular magnetic anisotropy}
Geometric control of the magnetization reversal in antidot lattices with perpendicular magnetic anisotropy

Gräfe, J., Weigand, M., Träger, N., Schütz, G., Goering, E. J., Skripnik, M., Nowak, U., Haering, F., Ziemann, P., Wiedwald, U.

{Physical Review B}, 93(10), American Physical Society, Woodbury, NY, 2016 (article)

Abstract
While the magnetic properties of nanoscaled antidot lattices in in-plane magnetized materials have widely been investigated, much less is known about the microscopic effect of hexagonal antidot lattice patterning on materials with perpendicular magnetic anisotropy. By using a combination of first-order reversal curve measurements, magnetic x-ray microscopy, and micromagnetic simulations we elucidate the microscopic origins of the switching field distributions that arise from the introduction of antidot lattices into out-of-plane magnetized GdFe thin films. Depending on the geometric parameters of the antidot lattice we find two regimes with different magnetization reversal processes. For small antidots, the reversal process is dominated by the exchange interaction and domain wall pinning at the antidots drives up the coercivity of the system. On the other hand, for large antidots the dipolar interaction is dominating which leads to fragmentation of the system into very small domains that can be envisaged as a basis for a bit patterned media.

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DOI Project Page Project Page [BibTex]

DOI Project Page Project Page [BibTex]


{Magnetic switching of nanoscale antidot lattices}
Magnetic switching of nanoscale antidot lattices

Wiedwald, U., Gräfe, J., Lebecki, K. M., Skripnik, M., Haering, F., Schütz, G., Ziemann, P., Goering, E., Nowak, U.

{Beilstein Journal of Nanotechnology}, 7, pages: 733-750, Beilstein-Institut, Frankfurt am Main, 2016 (article)

Abstract
We investigate the rich magnetic switching properties of nanoscale antidot lattices in the 200 nm regime. In-plane magnetized Fe, Co, and Permalloy (Py) as well as out-of-plane magnetized GdFe antidot films are prepared by a modified nanosphere lithography allowing for non-close packed voids in a magnetic film. We present a magnetometry protocol based on magneto-optical Kerr microscopy elucidating the switching modes using first-order reversal curves. The combination of various magnetometry and magnetic microscopy techniques as well as micromagnetic simulations delivers a thorough understanding of the switching modes. While part of the investigations has been published before, we summarize these results and add significant new insights in the magnetism of exchange-coupled antidot lattices.

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DOI Project Page [BibTex]

DOI Project Page [BibTex]


Map-Based Probabilistic Visual Self-Localization
Map-Based Probabilistic Visual Self-Localization

Brubaker, M. A., Geiger, A., Urtasun, R.

IEEE Trans. on Pattern Analysis and Machine Intelligence (PAMI), 2016 (article)

Abstract
Accurate and efficient self-localization is a critical problem for autonomous systems. This paper describes an affordable solution to vehicle self-localization which uses odometry computed from two video cameras and road maps as the sole inputs. The core of the method is a probabilistic model for which an efficient approximate inference algorithm is derived. The inference algorithm is able to utilize distributed computation in order to meet the real-time requirements of autonomous systems in some instances. Because of the probabilistic nature of the model the method is capable of coping with various sources of uncertainty including noise in the visual odometry and inherent ambiguities in the map (e.g., in a Manhattan world). By exploiting freely available, community developed maps and visual odometry measurements, the proposed method is able to localize a vehicle to 4m on average after 52 seconds of driving on maps which contain more than 2,150km of drivable roads.

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pdf Project Page [BibTex]

pdf Project Page [BibTex]


{Combined first-order reversal curve and x-ray microscopy investigation of magnetization reversal mechanisms in hexagonal antidot lattices}
Combined first-order reversal curve and x-ray microscopy investigation of magnetization reversal mechanisms in hexagonal antidot lattices

Gräfe, J., Weigand, M., Stahl, C., Träger, N., Kopp, M., Schütz, G., Goering, E. J., Haering, F., Ziemann, P., Wiedwald, U.

{Physical Review B}, 93(1), American Physical Society, Woodbury, NY, 2016 (article)

Abstract
The magnetization reversal in nanoscaled antidot lattices is widely investigated to understand the tunability of the magnetic anisotropy and the coercive field through nanostructuring of thin films. By investigating highly ordered focused ion beam milled antidot lattices with a combination of first-order reversal curves and magnetic x-ray microscopy, we fully elucidate the magnetization reversal along the distinct orientations of a hexagonal antidot lattice. This combination proves especially powerful as all partial steps of this complex magnetization reversal can be identified and subsequently imaged. Through this approach we discovered several additional steps that were neglected in previous studies. Furthermore, by imaging the microscopic magnetization state during each reversal step, we were able to link the coercive and interaction fields determined by the first-order reversal curve method to true microscopic magnetization configurations and determine their origin.

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DOI Project Page Project Page [BibTex]

DOI Project Page Project Page [BibTex]


{Switching probabilities of magnetic vortex core reversal studied by table top magneto optic Kerr microscopy}
Switching probabilities of magnetic vortex core reversal studied by table top magneto optic Kerr microscopy

Dieterle, G., Gangwar, A., Gräfe, J., Noske, M., Förster, J., Woltersdorf, G., Stoll, H., Back, C. H., Schütz, G.

{Applied Physics Letters}, 108(2), American Institute of Physics, Melville, NY, 2016 (article)

Abstract
We have studied vortex core reversal in a single submicron Permalloy disk by polar Kerr microscopy. A sophisticated lock-in-technique based on repetitive switching of the magnetic vortex core and a continuous calibration allows for a reliable determination of the switching probability. This highly sensitive method facilitates the detection of a change in the magnetic moment of the tiny magnetic vortex core which is about 1.5 × 10−17 A m2. We have investigated vortex core switching caused by excitation of the vortex core gyromode with varying frequencies and amplitudes. The frequency range in which switching occurs was found to broaden with increasing excitation amplitude, whereby the highest frequency in this range shifts stronger to higher frequencies than the lowest frequency to lower frequencies. The experimental results are in good agreement with micromagnetic simulations.

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DOI [BibTex]

DOI [BibTex]


{Pinned orbital moments - A new contribution to magnetic anisotropy}
Pinned orbital moments - A new contribution to magnetic anisotropy

Audehm, P., Schmidt, M., Brück, S., Tietze, T., Gräfe, J., Macke, S., Schütz, G., Goering, E.

{Scientific Reports}, 6, Nature Publishing Group, London, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Ab initio theory for ultrafast magnetization dynamics with a dynamic band structure

Müller, B. Y., Haag, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 414, pages: 14-18, North-Holland, Amsterdam, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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High-resolution analysis of currents at low-angle grain boundaries in YBCO thin films using magnetooptics and magnetic x-ray microscopy

Ruoß, S., Stahl, C., Bayer, J., Schütz, G., Albrecht, J., Laviano, F.

{IEEE Transactions on Applied Superconductivity}, 26(3), IEEE, New York, NY, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Three-dimensional character of the magnetization dynamics in magnetic vortex structures: Hybridization of flexure gyromodes with spin waves

Noske, M., Stoll, H., Fähnle, M., Gangwar, A., Woltersdorf, G., Slavin, A., Weigand, M., Dieterle, G., Förster, J., Back, C. H., Schütz, G.

{Physical Review Letters}, 117(3), American Physical Society, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Nanostructured materials for solid-state hydrogen storage: A review of the achievement of COST Action MP1103

Callini, E., Aguey-Zinsou, K., Ahuja, R., Ares, J. R., Bals, S., Biliskov, N., Chakraborty, S., Charalambopoulou, G., Chaudhary, A., Cuevas, F., Dam, B., de Jongh, P., Dornheim, M., Filinchuk, Y., Grbovic-Novakovic, J., Hirscher, M., Jensen, T. R., Jensen, P. B., Novakovic, N., Lai, Q., Leardini, F., Gattia, D. M., Pasquini, L., Steriotis, T., Turner, S., Vegge, T., Züttel, A., Montone, A.

{International Journal of Hydrogen Energy}, 41(32):14404-14428, Elsevier, Amsterdam, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic X-ray microscopy at low temperatures - Visualization of flux distributions in superconductors

Stahl, C., Ruoß, S., Weigand, M., Bechtel, M., Schütz, G., Albrecht, J.

{AIP Conference Proceedings}, 1696, AIP Publishing, Melville, NY, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Enhanced non-adiabaticity in vortex cores due to the emergent Hall effect

Bisig, A., Akosa, C. A., Moon, J., Rhensius, J., Moutafis, C., von Bieren, A., Heidler, J., Kiliani, G., Kammerer, M., Curcic, M., Weigand, M., Tyliszczak, T., Van Waeyenberge, B., Stoll, H., Schütz, G., Lee, K., Manchon, A., Kläui, M.

{Physical Review Letters}, 117(27), American Physical Society, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Quantitative magneto-optical analysis of the role of finite temperatures on the critical state in YBCO thin films

Albrecht, J., Brück, S., Stahl, C., Ruoß, S.

{Superconductor Science and Technology}, 29(11), IOP Pub., Bristol, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Collective modes in three-dimensional magnonic vortex crystals

Hänze, M., Adolff, C. F., Schulte, B., Möller, J., Weigand, M., Meier, G.

{Scientific Reports}, 6, Nature Publishing Group, London, UK, 2016 (article)

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DOI [BibTex]


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Spin wave mediated unidirectional vortex core reversal by two orthogonal monopolar field pulses: The essential role of three-dimensional magnetization dynamics

Noske, M., Stoll, H., Fähnle, M., Gangwar, A., Woltersdorf, G., Slavin, A., Weigand, M., Dieterle, G., Förster, J., Back, C. H., Schütz, G.

{Journal of Applied Physics}, 119(17), AIP Publishing, New York, NY, 2016 (article)

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DOI [BibTex]


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Magnetic vortex cores as tunable spin-wave emitters

Wintz, S., Tiberkevich, V., Weigand, M., Raabe, J., Lindner, J., Erbe, A., Slavin, A., Fassbender, J.

{Nature Nanotechnology}, 11(11):948-953, Nature Publishing Group, London, 2016 (article)

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DOI [BibTex]


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The usable capacity of porous materials for hydrogen storage

Schlichtenmayer, M., Hirscher, M.

{Applied Physics A}, 122(4), Springer-Verlag Heidelberg, Heidelberg, 2016 (article)

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DOI [BibTex]


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Ferromagnetic behaviour of ZnO: the role of grain boundaries

Straumal, B. B., Protasova, S. G., Mazilkin, A. A., Goering, E., Schütz, G., Straumal, P. B., Baretzky, B.

{Beilstein Journal of Nanotechnology}, 7, pages: 1936-1947, Beilstein-Institut, Frankfurt am Main, 2016 (article)

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DOI [BibTex]


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Localized domain wall nucleation dynamics in asymmetric ferromagnetic rings revealed by direct time-resolved magnetic imaging

Richter, K., Krone, A., Mawass, M., Krüger, B., Weigand, M., Stoll, H., Schütz, G., Kläui, M.

{Physical Review B}, 94(2), American Physical Society, Woodbury, NY, 2016 (article)

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DOI [BibTex]


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Observation of room-temperature magnetic skyrmions and their current-driven dynamics in ultrathin metallic ferromagnets

Woo, S., Litzius, K., Krüger, B., Im, M., Caretta, L., Richter, K., Mann, M., Krone, A., Reeve, R. M., Weigand, M., Agrawal, P., Lemesh, I., Mawass, M., Fischer, P., Kläui, M., Beach, G. S. D.

{Nature Materials}, 15(5):501-506, Nature Pub. Group, London, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]