Magnetic Proximity Effect in Perovskite Superconductor/Ferromagnet Multilayers

$\mathrm{YBa_2Cu_3O_7/La_{2/3}Ca_{1/3}MnO_3}$ superconducting/ferromagnetic (SC/FM) multilayers have been studied by neutron reflectometry. Evidence for a characteristic difference between the structural and magnetic depth profiles is obtained from the occurrence of a structurally forbidden Bragg peak in the FM state. The comparison with simulated reflectivity curves allows us to identify two possible magnetization profiles: a sizable magnetic moment within the SC layer antiparallel to the one in the FM layer (inverse proximity effect), or a ``dead'' region in the FM layer with zero net magnetic moment. The former scenario is supported by an anomalous SC-induced enhancement of the off-specular reflection, which testifies to a strong mutual interaction of SC and FM order parameters.Comment: 4 pages, 2 figures, submitted to PR

Self-assembled magnetic nanostructures of

\chem{CoPt_{3}}(111) nanostructures, prepared by self-assembled growth on \chem{WSe_{2}}(0001) substrates, present a 111-oriented fcc structure with a hexagonal island shape and a relatively narrow size distribution. \chem{L1_{2}}-type ordering is already observed in nanostructures grown at 150\un{{}^{\circ}C}, a temperature considerably lower than that required to order \chem{CoPt_{3}} continuous films. This change is attributed to the nanoscopic island shape, which increases the possibilities of surface atomic arrangements provided by the different growing facets. From the superparamagnetic behavior of the nanostructures, a strong decrease of magnetic anisotropy with the occurrence of \chem{L1_{2}} ordering is deduced

Einsturz des Kölner Stadtarchivs: Es droht Verjährung

http://www.wz.de/lokales/burscheid-region/koln-leverkusen/stadtarchiv-einsturz-es-droht-verjaehrung-1.2372550 http://www.express.de/koeln/stadtarchiv-einsturz-verjaehrung-droht--die-antworten-auf-die-acht-wichtigsten-fragen-2566147

Local spectroscopy of the Kondo lattice YbAl3: Seeing beyond the surface with scanning tunneling microscopy and spectroscopy

We report on an atomic-scale study of the Kondo lattice compound YbAl3 using scanning tunneling microscopy (STM) and spectroscopy (STS). An analysis of the surface orientation and structure is performed based on STM images containing more than one crystal facet. We compare tunneling spectra acquired on different facets and discuss their relation with the temperature scales observed in measurements of bulk quantities and the states observed in photoemission spectra. On specific facets, we observe strong additional resonances close to the Fermi energy which are not consistent with the characteristic energy scales found in bulk measurements, and which we interpret in terms of a modified Kondo state of the near-surface Ytterbium atoms