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2002


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Constructing Boosting algorithms from SVMs: an application to one-class classification.

Rätsch, G., Mika, S., Schölkopf, B., Müller, K.

IEEE Transactions on Pattern Analysis and Machine Intelligence, 24(9):1184-1199, September 2002 (article)

Abstract
We show via an equivalence of mathematical programs that a support vector (SV) algorithm can be translated into an equivalent boosting-like algorithm and vice versa. We exemplify this translation procedure for a new algorithm—one-class leveraging—starting from the one-class support vector machine (1-SVM). This is a first step toward unsupervised learning in a boosting framework. Building on so-called barrier methods known from the theory of constrained optimization, it returns a function, written as a convex combination of base hypotheses, that characterizes whether a given test point is likely to have been generated from the distribution underlying the training data. Simulations on one-class classification problems demonstrate the usefulness of our approach.

ei

DOI [BibTex]

2002


DOI [BibTex]


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The contributions of color to recognition memory for natural scenes

Wichmann, F., Sharpe, L., Gegenfurtner, K.

Journal of Experimental Psychology: Learning, Memory and Cognition, 28(3):509-520, May 2002 (article)

Abstract
The authors used a recognition memory paradigm to assess the influence of color information on visual memory for images of natural scenes. Subjects performed 5-10% better for colored than for black-and-white images independent of exposure duration. Experiment 2 indicated little influence of contrast once the images were suprathreshold, and Experiment 3 revealed that performance worsened when images were presented in color and tested in black and white, or vice versa, leading to the conclusion that the surface property color is part of the memory representation. Experiments 4 and 5 exclude the possibility that the superior recognition memory for colored images results solely from attentional factors or saliency. Finally, the recognition memory advantage disappears for falsely colored images of natural scenes: The improvement in recognition memory depends on the color congruence of presented images with learned knowledge about the color gamut found within natural scenes. The results can be accounted for within a multiple memory systems framework.

ei

PDF Web DOI [BibTex]

PDF Web DOI [BibTex]


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Training invariant support vector machines

DeCoste, D., Schölkopf, B.

Machine Learning, 46(1-3):161-190, January 2002 (article)

Abstract
Practical experience has shown that in order to obtain the best possible performance, prior knowledge about invariances of a classification problem at hand ought to be incorporated into the training procedure. We describe and review all known methods for doing so in support vector machines, provide experimental results, and discuss their respective merits. One of the significant new results reported in this work is our recent achievement of the lowest reported test error on the well-known MNIST digit recognition benchmark task, with SVM training times that are also significantly faster than previous SVM methods.

ei

PDF DOI [BibTex]

PDF DOI [BibTex]


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Contrast discrimination with sinusoidal gratings of different spatial frequency

Bird, C., Henning, G., Wichmann, F.

Journal of the Optical Society of America A, 19(7), pages: 1267-1273, 2002 (article)

Abstract
The detectability of contrast increments was measured as a function of the contrast of a masking or “pedestal” grating at a number of different spatial frequencies ranging from 2 to 16 cycles per degree of visual angle. The pedestal grating always had the same orientation, spatial frequency and phase as the signal. The shape of the contrast increment threshold versus pedestal contrast (TvC) functions depend of the performance level used to define the “threshold,” but when both axes are normalized by the contrast corresponding to 75% correct detection at each frequency, the (TvC) functions at a given performance level are identical. Confidence intervals on the slope of the rising part of the TvC functions are so wide that it is not possible with our data to reject Weber’s Law.

ei

PDF [BibTex]

PDF [BibTex]


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Support Vector Machines and Kernel Methods: The New Generation of Learning Machines

Cristianini, N., Schölkopf, B.

AI Magazine, 23(3):31-41, 2002 (article)

ei

[BibTex]


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Contrast discrimination with pulse-trains in pink noise

Henning, G., Bird, C., Wichmann, F.

Journal of the Optical Society of America A, 19(7), pages: 1259-1266, 2002 (article)

Abstract
Detection performance was measured with sinusoidal and pulse-train gratings. Although the 2.09-c/deg pulse-train, or line gratings, contained at least 8 harmonics all at equal contrast, they were no more detectable than their most detectable component. The addition of broadband pink noise designed to equalize the detectability of the components of the pulse train made the pulse train about a factor of four more detectable than any of its components. However, in contrast-discrimination experiments, with a pedestal or masking grating of the same form and phase as the signal and 15% contrast, the noise did not affect the discrimination performance of the pulse train relative to that obtained with its sinusoidal components. We discuss the implications of these observations for models of early vision in particular the implications for possible sources of internal noise.

ei

PDF [BibTex]

PDF [BibTex]


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Chirality-specific nonlinear spectroscopies in isotropic media

Fischer, P., Albrecht, A.

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 75(5):1119-1124, 2002, 10th International Conference on Time-Resolved Vibrational Spectroscopy (TRVS 2001), OKAZZAKI, JAPAN, MAY 21-25, 2001 (article)

Abstract
Sum or difference frequency generation (SFG or DFG) in isotropic media is in the electric-dipole approximation only symmetry allowed for optically active systems. The hyperpolarizability giving rise to these three-wave mixing processes features only one isotropic component. It factorizes into two terms, an energy (denominator) factor and a triple product of transition moments. These forbid degenerate SFG, i.e., second harmonic generation, as well as the existence of the linear electrooptic effect (Pockels effect) in isotropic media. This second order response also has no static limit, which leads to particularly strong resonance phenomena that are qualitatively different from those usually seen in the ubiquitous even-wave mixing spectroscopies. In particular, the participation of two (not the usual one) excited states is essential to achieve dramatic resonance enhancement, We report our first efforts to see such resonantly enhanced chirality specific SFG.

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DOI [BibTex]

DOI [BibTex]


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The chiral specificity of sum-frequency generation in solutions

Fischer, P., Beckwitt, K., Wise, F., Albrecht, A.

CHEMICAL PHYSICS LETTERS, 352(5-6):463-468, 2002 (article)

Abstract
Sum-frequency generation in isotropic media is in the electric-dipole approximation the only symmetry allowed for chiral systems. We demonstrate that the sum-frequency intensity from an optically active liquid depends quadratically on the difference in concentration of the two enantiomers. The dominant contribution to the signal is found to be due to the chirality specific electric-dipolar three-wave mixing nonlinearity. Selecting the polarization of all fields allows the chiral electric-dipolar contributions to the bulk sum-frequency signal to be discerned from any achiral magnetic-dipolar and electric-quadrupolar contributions. (C) 2002 Published by Elsevier Science B.V.

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DOI [BibTex]

DOI [BibTex]


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On optical rectification in isotropic media

Fischer, P., Albrecht, A.

LASER PHYSICS, 12(8):1177-1181, 2002 (article)

Abstract
Coherent nonlinear optical processes at second-order are only electric-dipole allowed in isotropic media that are optically active. Sum-frequency generation in chiral liquids has recently been observed, and difference-frequency and optical rectification have been predicted to exist in isotropic chiral media. Both Rayleigh-Schrodinger perturbation theory and the density matrix approach are used to discuss the quantum-chemical basis of optical rectification in optically active liquids. For pinene we compute the corresponding orientationally averaged hyperpolarizability, and estimate the light-induced dc electric polarization and the consequent voltage across a measuring capacitor it may give rise to near resonance.

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[BibTex]

[BibTex]


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Chemical processes during solid state reaction of carbon with alkali salts prepared for gravimetric hydrogen storage measurements

Skakalova, V., Quintel, A., Choi, Y. M., Roth, S., Becher, M., Hirscher, M.

{Chemical Physics Letters}, 365(3-4):333-337, 2002 (article)

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[BibTex]

[BibTex]


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Micromagnetic analysis of nucleation-hardened nanocrystalline PrFeB magnets

Kronmüller, H., Goll, D.

{Scripta Materialia}, 47(8):551-556, 2002 (article)

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[BibTex]

[BibTex]


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The Verwey transition in magnetite as studied by means of definite impurity doping

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

{Zeitschrift f\"ur Metallkunde}, 93(10):1095-1102, 2002 (article)

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[BibTex]

[BibTex]


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Antiparallel ruthenium coupling in doped La1.2Sr1.8Mn2-xRuxO7

Weigand, F., Gold, S., Schmid, A., Geissler, J., Goering, E., Dorr, K., Krabbes, G., Ruck, K.

{Applied Physics Letters}, 81(11):2035-2037, 2002 (article)

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[BibTex]

[BibTex]


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Micromagnetic theory of the pinning of domain walls at phase boundaries

Kronmüller, H., Goll, D.

{Physica B}, 319(1-4):122-126, 2002 (article)

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[BibTex]

[BibTex]


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Diffusion of oxygen in CdSe-photo sensor arrays

Klement, U., Ernst, F., Baretzky, B., Plitzko, J. M.

{Materials Science and Engineering B-Solid State Materials for Advanced Technology}, 94(2-3):123-130, 2002 (article)

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[BibTex]

[BibTex]


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Magnetic imaging with full-field soft X-ray microscopy

Fischer, P., Eimüller, T., Goll, D., Stoll, H., Puzic, A., Schütz, G., Denbeaux, G.

{Zeitschrift f\"ur Metallkunde}, 93(5):377-382, 2002 (article)

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[BibTex]

[BibTex]


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Magneto-optical studies of current distributions in high-Tc superconductors

Jooss, C., Albrecht, J., Kuhn, H., Leonhardt, S., Kronmüller, H.

{Reports on Progress in Physics}, 65(5):651-788, 2002 (article)

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[BibTex]

[BibTex]


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Dominant thermal defects in B2-FeAl

Bester, G., Meyer, B., Fähnle, M., Fu, C. L.

{Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing}, 323(1-2):487-490, 2002 (article)

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[BibTex]

[BibTex]


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Hydrogen desorption kinetics of nanostructured MgH2 composite materials

von Zeppelin, F., Reule, H., Hirscher, M.

{Journal of Alloys and Compounds}, 330, pages: 723-726, 2002 (article)

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[BibTex]

[BibTex]


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Hydrogen in mechanically prepared nanostructured h-BN: a critical comparison with that in nanostructured graphite

Wang, P., Orimo, S., Matsushima, T., Fujii, H., Majer, G.

{Applied Physics Letters}, 80(2):318-320, 2002 (article)

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[BibTex]

[BibTex]


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Enhancement of the critical current density by silver sheeting of YBCO thin films

Kienzle, M., Albrecht, J., Warthmann, R., Kronmüller, H., Leonhardt, S., Joos, C.

{Physical Review B}, 66, 2002 (article)

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[BibTex]

[BibTex]


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Pt magnetization profile in a Pt/Co bilayer studied by resonant magnetic x-ray reflectometry

Geissler, J., Goering, E., Justen, M., Weigand, F., Schütz, G., Langer, J., Schmitz, D., Maletta, H., Mattheis, R.

{Physical Review B}, 65, 2002 (article)

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DOI [BibTex]

DOI [BibTex]


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Imaging magnetic microstructures with soft x-ray microscopies

Fischer, P., Denbeaux, G., Nolting, F., Goll, D., Eimüller, T., Quitmann, C., Schütz, G.

{Transactions of the Magnetics Society of Japan}, 2, pages: 234-237, 2002 (article)

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[BibTex]

[BibTex]


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Positron age-momentum correlation (AMOC) measurements on organic liquids

Castellaz, P., Siegle, A., Stoll, H.

{Journal of Nuclear and Radiochemical Sciences}, 3, pages: R1-R7, 2002 (article)

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[BibTex]

[BibTex]


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Theory of crystal field states for heavy rare-earth impurities in MgB2

Welsch, F., Kremer, R., Fähnle, M.

{Journal of Physics-Condensed Matter}, 14(43):10273-10279, 2002 (article)

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[BibTex]

[BibTex]


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Micromagnetism and microstructure - tailoring of high- performance permanent magnets

Goll, D.

{Zeitschrift f\"ur Metallkunde}, 93(10):1009-1018, 2002 (article)

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[BibTex]

[BibTex]


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Interplay between chemical and magnetic roughness of Pt in a Pt/Co bilayer investigated with X-ray resonant magnetic reflectometry

Geissler, J., Goering, E., Weigand, F., Schütz, G.

{Zeitschrift f\"ur Metallkunde}, 93(10):946-952, 2002 (article)

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Direct correlation of Cr 3d orbital polarization and O K-edge X-ray magnetic circular dichroism of epitaxial CrO2 films

Goering, E., Bayer, A., Gold, S., Schütz, G., Rabe, M., Rüdiger, U., Güntherodt, G.

{Europhysics Letters}, 58(6):906-911, 2002 (article)

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[BibTex]


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Surface magnetization reversal of sputtered CrO2

Goering, E., Gold, S., Will, J.

{Zeitschrift f\"ur Metallkunde}, 93(5):372-376, 2002 (article)

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[BibTex]

[BibTex]


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Shear-strain-related nonlinear magnetoelastic properties of epitaxial films

Komelj, M., Fähnle, M.

{Physical Review B}, 65(9), 2002 (article)

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[BibTex]

[BibTex]


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NMR studies of hydrogen diffusion in the hydrogen-stabilized Laves phase compound C15-HfTi2Hx

Eberle, U., Majer, G., Skripov, A. V., Kozhanov, V. N.

{Journal of Physics-Condensed Matter}, 14(2):153-164, 2002 (article)

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[BibTex]

[BibTex]


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The existence of more than one jump process of hydrogen in palladium-silver alloys - an NMR study

Züchner, H., Barlag, H., Majer, G.

{Journal of Alloys and Compounds}, 330-332, pages: 448-453, 2002 (article)

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[BibTex]

[BibTex]


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Electric field distribution at low-angle grain boundaries in high-temperature superconductors

Jooss, C., Guth, K., Born, V., Albrecht, J.

{Physical Review B}, 65(1), 2002 (article)

mms

[BibTex]

[BibTex]


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Finite element calculations on the single-domain limit of a ferromagnetic cube - a solution to \microMAG Standard Problem No. 3

Hertel, R., Kronmüller, H.

{Journal of Magnetism and Magnetic Materials}, 238(2-3):185-199, 2002 (article)

mms

[BibTex]

[BibTex]


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Diffusion of oxygen in CdSe-photosensor arrays

Klement, U., Ernst, F., Baretzky, B., Plitzko, J. M.

{Materials Science and Engineering B}, 94, pages: 123-130, 2002 (article)

mms

[BibTex]

[BibTex]


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Influence of the grain boundary phase transitions on the diffusion-related properties

Straumal, B., Baretzky, B.

{Diffusion and Defect Forum}, 216-217, pages: 53-64, 2002 (article)

mms

[BibTex]

[BibTex]


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Magneto-optical studies of flux pinning in high-temperature superconductors

Jooss, C., Albrecht, J.

{Zeitschrift f\"ur Metallkunde}, 93(10):1065-1070, 2002 (article)

mms

[BibTex]

[BibTex]


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From the bulk to monatomic wires: An ab initio study of magnetism in Co systems with various dimensionality

Komelj, M., Ederer, C., Davenport, J. W., Fähnle, M.

{Physical Review B}, 66(14), 2002 (article)

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[BibTex]

[BibTex]


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The initial stages of oxidation of γ-TiAl: an X-ray photoelectron study

Schmiedgen, M., Graat, P. C. J., Baretzky, B., Mittemeijer, E. J.

{Thin Solid Films}, 415(1-2):114-122, 2002 (article)

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[BibTex]

[BibTex]


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Morphology and thermal stability of metal contacts on crystalline organic thin films

Dürr, A. C., Schreiber, F., Kelsch, M., Carstanjen, H. D., Dosch, H.

{Advanced Materials}, 14(13-14):961-963, 2002 (article)

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[BibTex]

[BibTex]


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Magnetic anisotropy of textured CrO2 thin films investigated by X-ray magnetic circular dichroism

Goering, E., Justen, M., Geissler, J., Rüdiger, U., Rabe, M., Güntherodt, G., Schütz, G.

{Applied Physics A-Materials Science \& Processing}, 74(6):747-753, 2002 (article)

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[BibTex]

[BibTex]


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Identification of nanocrystal nucleation and growth in Al85Ni5Y8CO2 metallic glass with quenched-in nuclei

Wang, J. Q., Zhang, H. W., Gu, X. J., Lu, K., Sommer, F., Mittemeijer, E. J.

{Applied Physics Letters}, 80(18):3319-3321, 2002 (article)

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[BibTex]

[BibTex]


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Master equations for the concentrations of atomic defects in B2 compounds

Meyer, B., Fähnle, M.

{Physica Status Solidi B-Basic Research}, 229(3):1139-1143, 2002 (article)

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[BibTex]

[BibTex]


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On the electronic structure of the pure and oxygen covered Ru(0001) surface

Bester, G., Fähnle, M.

{Surface Science}, 497(1-3):305-310, 2002 (article)

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[BibTex]

[BibTex]


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Atomic defects and diffusion in intermetallic compounds: The impact of the ab initio electron theory

Fähnle, M.

{Diffusion and Defect Forum}, 203-205, pages: 37-46, 2002 (article)

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[BibTex]

[BibTex]


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Switching behavior of single nanowires inside dense nickel nanowire arrays

Nielsch, K., Hertel, R., Wehrspohn, R. B., Barthel, J., Kirschner, J., Gösele, U., Fischer, S. F., Kronmüller, H.

{IEEE Transactions on Magnetics}, 38(5):2571-2573, 2002 (article)

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[BibTex]


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On the magnetoelastic contribution to the magnetic anisotropy of thin epitaxial Permalloy films: an ab initio study

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 238(2-3):L125-L128, 2002 (article)

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[BibTex]

[BibTex]


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Nanostructured graphite-hydrogen systems prepared by mechanical milling method

Orimo, S. I., Matsushima, T., Fujii, H., Fukunaga, T., Majer, G., Zuttel, A., Schlapbach, L.

{Molecular Crystals and Liquid Crystals}, 386, pages: 173-178, 2002 (article)

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[BibTex]

[BibTex]


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Micromagnetic analysis of pinning-hardened nanostructured, nanocrystalline Sm2Co17 based alloys

Kronmüller, H., Goll, D.

{Scripta Materialia}, 47, pages: 545-550, 2002 (article)

mms

[BibTex]

[BibTex]