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2019


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Series Elastic Behavior of Biarticular Muscle-Tendon Structure in a Robotic Leg

Ruppert, F., Badri-Spröwitz, A.

Frontiers in Neurorobotics, 64, pages: 13, 13, August 2019 (article)

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Frontiers YouTube link (url) DOI [BibTex]

2019


Frontiers YouTube link (url) DOI [BibTex]


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Beyond Basins of Attraction: Quantifying Robustness of Natural Dynamics

Steve Heim, , Spröwitz, A.

IEEE Transactions on Robotics (T-RO) , 35(4), pages: 939-952, August 2019 (article)

Abstract
Properly designing a system to exhibit favorable natural dynamics can greatly simplify designing or learning the control policy. However, it is still unclear what constitutes favorable natural dynamics and how to quantify its effect. Most studies of simple walking and running models have focused on the basins of attraction of passive limit cycles and the notion of self-stability. We instead emphasize the importance of stepping beyond basins of attraction. In this paper, we show an approach based on viability theory to quantify robust sets in state-action space. These sets are valid for the family of all robust control policies, which allows us to quantify the robustness inherent to the natural dynamics before designing the control policy or specifying a control objective. We illustrate our formulation using spring-mass models, simple low-dimensional models of running systems. We then show an example application by optimizing robustness of a simulated planar monoped, using a gradient-free optimization scheme. Both case studies result in a nonlinear effective stiffness providing more robustness.

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arXiv preprint arXiv:1806.08081 T-RO link (url) DOI Project Page [BibTex]

arXiv preprint arXiv:1806.08081 T-RO link (url) DOI Project Page [BibTex]


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X-ray Optics Fabrication Using Unorthodox Approaches

Sanli, U., Baluktsian, M., Ceylan, H., Sitti, M., Weigand, M., Schütz, G., Keskinbora, K.

Bulletin of the American Physical Society, APS, 2019 (article)

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[BibTex]

[BibTex]


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Nanoscale detection of spin wave deflection angles in permalloy

Gross, F., Träger, N., Förster, J., Weigand, M., Schütz, G., Gräfe, J.

{Applied Physics Letters}, 114(1), American Institute of Physics, Melville, NY, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Coherent excitation of heterosymmetric spin waves with ultrashort wavelengths

Dieterle, G., Förster, J., Stoll, H., Semisalova, A. S., Finizio, S., Gangwar, A., Weigand, M., Noske, M., Fähnle, M., Bykova, I., Gräfe, J., Bozhko, D. A., Musiienko-Shmarova, H. Y., Tiberkevich, V., Slavin, A. N., Back, C. H., Raabe, J., Schütz, G., Wintz, S.

{Physical Review Letters}, 122(11), American Physical Society, Woodbury, N.Y., 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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A special issue on hydrogen-based Energy storage
{International Journal of Hydrogen Energy}, 44, pages: 7737, Elsevier, Amsterdam, 2019 (misc)

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DOI [BibTex]

DOI [BibTex]


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Reprogrammability and Scalability of Magnonic Fibonacci Quasicrystals

Lisiecki, F., Rychły, J., Kuświk, P., Głowiński, H., Kłos, J. W., Groß, F., Bykova, I., Weigand, M., Zelent, M., Goering, E. J., Schütz, G., Gubbiotti, G., Krawczyk, M., Stobiecki, F., Dubowik, J., Gräfe, J.

Physical Review Applied, 11, pages: 054003, 2019 (article)

Abstract
Magnonic crystals are systems that can be used to design and tune the dynamic properties of magnetization. Here, we focus on one-dimensional Fibonacci magnonic quasicrystals. We confirm the existence of collective spin waves propagating through the structure as well as dispersionless modes; the reprogammability of the resonance frequencies, dependent on the magnetization order; and dynamic spin-wave interactions. With the fundamental understanding of these properties, we lay a foundation for the scalable and advanced design of spin-wave band structures for spintronic, microwave, and magnonic applications.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Nanoscale X-ray imaging of spin dynamics in Yttrium iron garnet

Förster, J., Wintz, S., Bailey, J., Finizio, S., Josten, E., Meertens, D., Dubs, C., Bozhko, D. A., Stoll, H., Dieterle, G., Traeger, N., Raabe, J., Slavin, A. N., Weigand, M., Gräfe, J., Schütz, G.

2019 (misc)

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link (url) [BibTex]

link (url) [BibTex]


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Interpreting first-order reversal curves beyond the Preisach model: An experimental permalloy microarray investigation

Groß, F., Ilse, S. E., Schütz, G., Gräfe, J., Goering, E.

{Physical Review B}, 99(6), American Physical Society, Woodbury, NY, 2019 (article)

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DOI [BibTex]


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Bistability of magnetic states in Fe-Pd nanocap arrays

Aravind, P. B., Heigl, M., Fix, M., Groß, F., Gräfe, J., Mary, A., Rajgowrav, C. R., Krupiński, M., Marszałek, M., Thomas, S., Anantharaman, M. R., Albrecht, M.

Nanotechnology, 30, pages: 405705, 2019 (article)

Abstract
Magnetic bistability between vortex and single domain states in nanostructures are of great interest from both fundamental and technological perspectives. In soft magnetic nanostructures, the transition from a uniform collinear magnetic state to a vortex state (or vice versa) induced by a magnetic field involves an energy barrier. If the thermal energy is large enough for overcoming this energy barrier, magnetic bistability with a hysteresis-free switching occurs between the two magnetic states. In this work, we tune this energy barrier by tailoring the composition of FePd alloys, which were deposited onto self-assembled particle arrays forming magnetic vortex structures on top of the particles. The bifurcation temperature, where a hysteresis-free transition occurs, was extracted from the temperature dependence of the annihilation and nucleation field which increases almost linearly with Fe content of the magnetic alloy. This study provides insights into the magnetization reversal process associated with magnetic bistability, which allows adjusting the bifurcation temperature range by the material properties of the nanosystem.

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link (url) [BibTex]

link (url) [BibTex]


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Artifacts from manganese reduction in rock samples prepared by focused ion beam (FIB) slicing for X-ray microspectroscopy

Macholdt, D. S., Förster, J., Müller, M., Weber, B., Kappl, M., Kilcoyne, A. L. D., Weigand, M., Leitner, J., Jochum, K. P., Pöhlker, C., Andreae, M. O.

{Geoscientific instrumentation, methods and data systems}, 8(1):97-111, Copernicus Publ., Göttingen, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Mixed-state magnetotransport properties of MgB2 thin film prepared by pulsed laser deposition on an Al2O3 substrate

Alzayed, N. S., Shahabuddin, M., Ramey, S. M., Soltan, S.

{Journal of Materials Science: Materials in Electronics}, 30(2):1547-1552, Springer, Norwell, MA, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Comparison of theories of fast and ultrafast magnetization dynamics

Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 469, pages: 28-29, NH, Elsevier, Amsterdam, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Concepts for improving hydrogen storage in nanoporous materials

Broom, D. P., Webb, C. J., Fanourgakis, G. S., Froudakis, G. E., Trikalitis, P. N., Hirscher, M.

{International Journal of Hydrogen Energy}, 44(15):7768-7779, Elsevier, Amsterdam, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Controlling dislocation nucleation-mediatd plasticity in nanostructures via surface modification

Shin, J., Chen, L. Y., Sanli, U. T., Richter, G., Labat, S., Richard, M., Cornelius, T., Thomas, O., Gianola, D. S.

{Acta Materialia}, 166, pages: 572-586, Elsevier Science, Kidlington, 2019 (article)

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DOI [BibTex]

DOI [BibTex]

2007


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Hydrogen storage in metal-organic frameworks

Hirscher, M., Panella, B.

{Scripta Materialia}, 56, pages: 809-812, 2007 (article)

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[BibTex]

2007


[BibTex]


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Substrate-induced current anisotropy in YBa2Cu3O7-δthin films

Djupmyr, M., Albrecht, J.

{Physica C}, 460-462, pages: 1190-1191, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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A micellar approach to magnetic ultrahigh-density data-storage media: extending the limits of current colloidal methods

Ethirajan, A., Wiedwald, U., Boyen, H.-G., Kern, B., Han, L., Klimmer, A., Weigl, F., Kästle, G., Ziemann, P., Fauth, K., Cai, J., Behm, J., Romanyuk, A., Oelhafen, P., Walther, P., Biskupek, J., Kaiser, U.

{Advanced Materials}, 19, pages: 406-410, 2007 (article)

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[BibTex]

[BibTex]


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Size dependence in the magnetization reversal of Fe/Gd multilayers on self-assembled arrays of nanospheres

Amaladass, E., Ludescher, B., Schütz, G., Tyliszczak, T., Eimüller, T.

{Applied Physics Letters}, 91, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Ma\ssgeschneiderte Wasserstoffspeicher

Hirscher, M., Panella, B.

{Nachrichten aus der Gdch-Energieinitiative}, (Sonderheft April 2007):12-13, 2007 (article)

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[BibTex]

[BibTex]


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Reconstruction of historical alloys for pipe organs brings true Baroque music back to life.

Baretzky, B., Friesel, M., Straumal, B.

{MRS Bulletin}, 32, pages: 249-255, 2007 (article)

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[BibTex]

[BibTex]


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Analysis of results from X-ray magnetic reflectometry for magnetic multilayer systems

Fähnle, M., Steiauf, D., Martosiswoyo, L., Goering, E., Brück, S., Schütz, G.

{Physical Review B}, 75, 2007 (article)

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[BibTex]

[BibTex]


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Dramatic role of critical current anisotropy on flux avalanches in MgB2 films

Albrecht, J., Matveev, A. T., Strempfer, J., Habermeier, H.-U., Shantsev, D. V., Galperin, Y. M., Johansen, T. H.

{Physical Review Letters}, 98, 2007 (article)

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[BibTex]

[BibTex]


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Transport properties of LCMO/YBCO hybrid structures

Soltan, S., Albrecht, J., Habermeier, H.-U.

{Materials Science and Engineering B}, 144, pages: 15-18, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Cluster expansions in multicomponent systems: precise expansions from noisy databases

Diaz-Ortiz, A., Dosch, H., Drautz, R.

{Journal of Physics: Condensed Matter}, 19, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Unusual propagation of magnetic avalanches in gold covered MgB2

Albrecht, J., Matveev, A. T., Habermeier, H.-U.

{Physica C}, 460-462, pages: 1245-1246, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Lowering of the L10 ordering temperature of FePt nanoparticles by He+ ion irradiation

Wiedwald, U., Klimmer, A., Kern, B., Han, L., Boyen, H.-G., Ziemann, P., Fauth, K.

{Applied Physics Letters}, 90, 2007 (article)

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[BibTex]

[BibTex]


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Magnetic core shell nanoparticles characterized by X-ray absorption and magnetic circular dichroism

Fauth, K.

{Modern Physics Letters B}, 21(18):1179-1187, 2007 (article)

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[BibTex]

[BibTex]


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Magnetic moment of Fe in oxide-free FePt nanoparticles

Dmitrieva, O., Spasova, M., Antoniak, C., Acet, M., Dumpich, G., Kästner, J., Farle, M., Fauth, K., Wiedwald, U., Boyen, H.-G., Ziemann, P.

{Physical Review B}, 76, 2007 (article)

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[BibTex]

[BibTex]


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The effect of bismuth segregation on the faceting of \Sigma3 and \Sigma9 coincidence boundaries in copper bicrystals

Straumal, B. B., Polyakov, S. A., Chang, L.-S., Mittemeijer, E. J.

{International Journal of Materials Research}, 98, pages: 451-456, 2007 (article)

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[BibTex]

[BibTex]


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Hot isostatic pressing of Cu-Bi polycrystals with liquid-like grain boundary layers

Chang, L.-S., Straumal, B., Rabkin, E., Lojkowski, W., Gust, W.

{Acta Materialia}, 55, pages: 335-343, 2007 (article)

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[BibTex]

[BibTex]


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Spatially resolved magnetic response in core shell nanoparticles

Fauth, K., Goering, E., Theil Kuhn, L.

{Modern Physics Letters B}, 21(18):1197-1200, 2007 (article)

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[BibTex]

[BibTex]


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Interfaces in semiconductor/metal radial superlattices

Deneke, C., Sigle, W., Eigenthaler, U., van Aken, P. A., Schütz, G., Schmidt, O. G.

{Applied Physics Letters}, 90, 2007 (article)

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[BibTex]

[BibTex]


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Live cell adhesion assay with attenuated total reflection infrared spectroscopy

Schmidt, M., Wolfram, T., Rumpler, M., Tripp, C. P., Grunze, M.

{Biointerphases}, 2(1):1-5, 2007 (article)

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[BibTex]

[BibTex]


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Unusual Co moment reduction in the NiCoO/Co exchange bias system

Brück, S., Goering, E., Tang, Y. J., Schütz, G., Berkowitz, A. E.

{Journal of Magnetism and Magnetic Materials}, 310, pages: 2316-2318, 2007 (article)

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[BibTex]

[BibTex]


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Ab initio calculations of adiabatic magnon spectra using the atomic-sphere aproximation for the spin direction

Singer, R., Dietermann, F., Steiauf, D., Fähnle, M.

{Physical Review B}, 76, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Low-temperature thermal-desorption mass spectroscopy applied to investigate the hydrogen adsorption on porous materials

Panella, B., Hirscher, M., Ludescher, B.

{Microporous and Mesoporous Materials}, 103, pages: 230-234, 2007 (article)

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[BibTex]


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Dependence of the critical temperature of YBCO thin films on spinpolarized quasiparticle injection

Habermeier, H.-U., Soltan, S., Albrecht, J.

{International Journal of Modern Physics B}, 21(18 \& 19):3303-3306, 2007 (article)

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[BibTex]

[BibTex]


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Copper alloys for the restoration of reed pipes in historic organs

Straumal, B. B., Baretzky, B., Kalnins, J., Aslund, A., Friesel, M.

{Journal of Functional Materials}, 1, pages: 4-10, 2007 (article)

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[BibTex]

[BibTex]


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Inhomogeneous vortex distribution and magnetic coupling in oxide superconductor-ferromagnet hybrids

Albrecht, J., Djupmyr, M., Soltan, S., Habermeier, H.-U., Connolly, M. R., Bending, S. J.

{New Journal of Physics}, 9, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Metal hydride materials for solid hydrogen storage: a review

Sakintuna, B., Lamari-Darkrim, F., Hirscher, M.

{International Journal of Hydrogen Energy}, 32, pages: 1121-1140, 2007 (article)

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[BibTex]

[BibTex]


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Thermal reversal of exchange spring composite media in magnetic fields

Goll, D., Macke, S., Bertram, H. N.

{Applied Physics Letters}, 90, 2007 (article)

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[BibTex]

[BibTex]


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Magnetism of Co-doped ZnO thin films

Gacic, M., Jakob, G., Herbort, C., Adrian, H., Tietze, T., Brück, S., Goering, E.

{Physical Review B}, 75, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Universal temperature scaling of flux line pinning in high-temperature superconducting thin films

Albrecht, J., Djupmyr, M., Brück, S.

{Journal of Physics: Condensed Matter}, 19, 2007 (article)

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[BibTex]

[BibTex]


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Dependence of the critical temperature of YBCO thin films on spin-polarized quasiparticle injection

Habermeier, H.-U., Soltan, S., Albrecht, J.

{Physica C}, 460-462, pages: 32-35, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Interaction of ferromagnetic LCMO layers through a superconducting YBCO spacer

Ravikumar, G., Yashwant, G., Singh, M. R., Gupta, S. K., Bhattacharya, S., Soltan, S., Albrecht, J., Habermeier, H.-U.

{Physica C}, 460-462, pages: 1375-1376, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Vortex dynamics in Permalloy disks with artificial defects: suppression of the gyrotropic mode

Kuepper, K., Bischoff, L., Akhmadaliev, C., Fassbinder, J., Stoll, H., Chou, K., Puzic, A., Fauth, K., Dolgos, D., Schütz, G., Van Waeyenberge, B., Tyliszczak, T., Neudecker, I., Woltersdorf, G., Back, C.

{Appplied Physics Letters}, 90, 2007 (article)

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[BibTex]

[BibTex]


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Vacancy-interstitial annihilation in titanomagnetite by thermal annealing

Walz, F., Brabers, V. A. M., Brabers, J. H. V. J., Kronmüller, H.

{Physica Status Solidi (A)}, 204(10):3514-3525, 2007 (article)

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DOI [BibTex]

DOI [BibTex]