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When a thin elastic foil with high shear modulus and low bending rigidity is crumpled by an external force, the stretching and bending energies are not distributed uniformly, but condense into localized folds and conical dislocations. A familiar example for such a material is paper. The crumpling process can be studied very well by computer simulations. The picture shows a a circular piece of an originally flat, thin elastic sheet, which has been compressed by a constant isotropic force to about a third of its original (linear) size. A characteristic pattern of folds has formed, which is shown here in the flat reference state. Coloring is used to indicate the sharpness of the folds where yellow means a nearly flat surface, blue indicates weakly curved regions while strongly curved folds are shown in red.  Persistent
Identifier: urn:nbn:de:0001-00070
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Polarised neutron diffraction under grazing incidence from an optical grating covered with a Nickel layer. Data were obtained on the reflectometer "HADAS" in the neutron guide hall ELLA at the DIDO reactor. The graph shows the count rate in the "up-up"-channel (i.e. scattering without change of polarisation) as function of the angle of incidence (abscissa) and exit (ordinate). From the full polarisation dependence, structural and magnetic contributions can be separated and the magnetic roughness and shape anisotropy can be determined. Persistent
Identifier: urn:nbn:de:0001-00064
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Atomic view of a monatomic film of magnetic manganese atoms deposited on a (110) oriented tungsten surface, Mn/W(110). The magnetic moments indicated by arrows are arranged in an antiferromagnetic order, a checkerboard arrangement of red and green atoms. All Mn atoms are chemically and structurally indistinguishable and differ only in the relative orientation of the magnetic moments. The total magnetization is zero. This atomic scale magnetic structure can be detected using a spin-polarized scanning tunneling microscope (SP-STM)... Persistent
Identifier: urn:nbn:de:0001-00056
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Topography of polished (100)-surfaces of various single crystals of SrTiO3, obtained by AFM after thermal treatment at ambient pressure. All surfaces exhibit the same characteristics changes compared to the original surface prior to heat treatment, namely the formation of the step-like terraces and the appearence of the droplet-like features on top of the surface. Persistent
Identifier: urn:nbn:de:0001-00041
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Atomic view of a complex arrangment of twin boundaries in the electroceramic material barium titanate (BaTiO3). The pseudocolour image shows the phase of a quantum mechanical electron wave function which was reconstructed numerically from a series of high-resolution transmission electron microscopy (HRTEM) images. In contrast to an image, the interpretation of the quantum mechanical phase is straight forward, because the latter is free from the severe imaging artefacts introduced by the observation instrument... Persistent
Identifier: urn:nbn:de:0001-00039
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© Forschungszentrum JülichOnline 2002
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