| 1. |
- Chang, J., et al.
(författare)
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Anisotropic breakdown of Fermi liquid quasiparticle excitations in overdoped La2-xSrxCuO4
- 2013
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4, s. 2559-
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature superconductivity emerges from an un-conventional metallic state. This has stimulated strong efforts to understand exactly how Fermi liquids breakdown and evolve into an un-conventional metal. A fundamental question is how Fermi liquid quasiparticle excitations break down in momentum space. Here we show, using angle-resolved photoemission spectroscopy, that the Fermi liquid quasiparticle excitations of the overdoped superconducting cuprate La1.77Sr0.23CuO4 is highly anisotropic in momentum space. The quasiparticle scattering and residue behave differently along the Fermi surface and hence the Kadowaki-Wood's relation is not obeyed. This kind of Fermi liquid breakdown may apply to a wide range of strongly correlated metal systems where spin fluctuations are present.
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| 2. |
- Fatuzzo, C. G., et al.
(författare)
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Nodal Landau Fermi-liquid quasiparticles in overdoped La1.77Sr0.23CuO4
- 2014
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:20, s. 205104-
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Tidskriftsartikel (refereegranskat)abstract
- Nodal angle-resolved photoemission spectra taken on overdoped La1.77Sr0.23CuO4 are presented and analyzed. It is proven that the low-energy excitations are true Landau Fermi-liquid quasiparticles. We show that momentum and energy distribution curves can be analyzed self-consistently without quantitative knowledge of the bare band dispersion. Finally, by imposing Kramers-Kronig consistency on the self-energy Sigma, insight into the quasiparticle residue is gained. We conclude by comparing our results to quasiparticle properties extracted from thermodynamic, magnetoresistance, and high-field quantum oscillation experiments on overdoped Tl2Ba2CuO6+delta.
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| 3. |
- Lundgren, Jolanta L, et al.
(författare)
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Activity-independent release of the amyloid β-peptide from rat brain nerve terminals.
- 2014
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 566:Mar 3, s. 125-130
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Tidskriftsartikel (refereegranskat)abstract
- Synaptic degeneration is one of the earliest hallmarks of Alzheimer disease. The molecular mechanism underlying this degeneration is not fully elucidated but one key player appears to be the synaptotoxic amyloid β-peptide (Aβ). The exact localization of the production of Aβ and the mechanisms whereby Aβ is released remain elusive. We have earlier shown that Aβ can be produced in crude synaptic vesicle fractions and it has been reported that increased synaptic activity results in increased secreted but decreased intracellular Aβ levels. Therefore, we considered whether Aβ could be produced in synaptic vesicles and/or released through the same mechanisms as neurotransmitters in synaptic vesicle exocytosis. Small amounts of Aβ were found to be produced in pure synaptic vesicle preparations. We also studied the release of glutamate and Aβ from rat cortical nerve terminals (synaptosomes). We found that large amounts of Aβ were secreted from non-stimulated synaptosomes, from which glutamate was not released. On the contrary, we could not detect any differences in Aβ release between non-stimulated synaptosomes and synaptosomes stimulated with KCl or 4-aminopyridine, whereas glutamate release was readily inducible in this system. To conclude, our results indicate that the major release mechanism of Aβ from isolated nerve terminals differs from the synaptic release of glutamate and that the activity-dependent increase of secreted Aβ, reported by several groups using intact cells, is likely dependent on post-synaptic events, trafficking and/or protein synthesis mechanisms.
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| 4. |
- Razzoli, E., et al.
(författare)
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The Fermi surface and band folding in La2-xSrxCuO4, probed by angle-resolved photoemission
- 2010
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12, s. 125003-
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Tidskriftsartikel (refereegranskat)abstract
- A systematic angle-resolved photoemission study of the electronic structure of La2-xSrxCuO4 in a wide doping range is presented in this paper. In addition to the main energy band, we observed a weaker additional band, the (pi, pi) folded band, which shows unusual doping dependence. The appearance of the folded band suggests that a Fermi surface reconstruction is doping dependent and could already occur at zero magnetic field.
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