3,984 research outputs found

    Magnetic anisotropy in Shiba bound states across a quantum phase transition

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    The exchange coupling between magnetic adsorbates and a superconducting substrate leads to Shiba states inside the superconducting energy gap and a Kondo resonance outside the gap. The exchange coupling strength determines whether the quantum many-body ground state is a Kondo singlet or a singlet of the paired superconducting quasiparticles. Here, we use scanning tunneling spectroscopy to identify the different quantum ground states of Manganese phthalocyanine on Pb(111). We observe Shiba states, which are split into triplets by magnetocrystalline anisotropy. Their characteristic spectral weight yields an unambiguous proof of the nature of the quantum ground state.Comment: 6 pages, 4 figure

    Geographic origin of meat—elements of an analytical approach to its authentication

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    This review article discusses recent analytical developments with respect to the determination of the geographic origin of raw meat. The main emphasis is laid on lamb, beef and poultry. So far, some methods have shown quite promising potential (e.g. stable isotope ratios, trace elements), others have remained unsatisfactory in their discriminating power to authenticate the geographic origin of meat (e.g. microbiological profile, sensory traits, volatile compounds). Other methods (e.g. animal genotype, gross chemical composition) could be auxiliary criteria as they help to determine related indicators such as feeding or housing conditions but not directly the origin. The complexity of this question is large. An integrated approach simultaneously addressing various species and production characteristics such as environment, animal husbandry conditions, breed, feeding and drinking water has to be developed. Strategies have to be different for global and micro-regional scale

    Natural segregation of nucleolar components in the course of plant cell differentiation

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    Segregation of the nucleolar components is described in the differentiated nucleus of the generative cell in the growing Clivia and Lilium pollen tubes. This finding of a natural nucleolar segregation is discussed against the background of current views of the correlations of nucleolar morphology and transcriptional activity

    End states and subgap structure in proximity-coupled chains of magnetic adatoms

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    A recent experiment [Nadj-Perge et al., Science 346, 602 (2014)] provides evidence for Majorana zero modes in iron (Fe) chains on the superconducting Pb(110) surface. Here, we study this system by scanning tunneling microscopy using superconducting tips. This high-resolution technique resolves a rich subgap structure, including zero-energy excitations in some chains. We compare the symmetry properties of the data under voltage reversal against theoretical expectations and provide evidence that the putative Majorana signature overlaps with a previously unresolved low-energy resonance. Interpreting the data within a Majorana framework suggests that the topological gap is significantly smaller than previously believed. Aided by model calculations, we also analyze higher-energy features of the subgap spectrum and their relation to high-bias peaks which we associate with the Fe d-bands.Comment: 5+5 pages, 5+6 figure
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