977 research outputs found
Anomalous peak in the superconducting condensate density of cuprate high T_{c} superconductors at a unique critical doping state
The doping dependence of the superconducting condensate density, n_{s}^{o},
has been studied by muon-spin-rotation for
Y_{0.8}Ca_{0.2}Ba_{2}(Cu_{1-z}Zn_{z})_{3}O_{7-\delta} and
Tl_{0.5-y}Pb_{0.5+y}Sr_{2}Ca_{1-x}Y_{x}Cu_{2}O_{7}. We find that n_{s}^{o}
exhibits a pronounced peak at a unique doping state in the slightly overdoped
regime. Its position coincides with the critical doping state where the normal
state pseudogap first appears depleting the electronic density of states. A
surprising correlation between n_{s}^{o} and the condensation energy U_{o} is
observed which suggests unconventional behavior even in the overdoped region.Comment: 10 pages, 3 figure
Recherches sur l’écosystème de la forêt subéquatoriale de basse Côte-d’Ivoire V. Biomasse végétale et productivité primaire cycle de la matière organique
Coexistence of ferromagnetism and superconductivity in the hybrid ruthenate-cuprate compound RuSr_2GdCu_2O_8 studied by muon spin rotation (\mu SR) and DC-magnetization
We have investigated the magnetic and the superconducting properties of the
hybrid ruthenate-cuprate compound RuSr_{2}GdCu_{2}O_{8} by means of zero-field
muon spin rotation- (ZF-SR) and DC magnetization measurements. The
DC-magnetisation data establish that this material exhibits ferromagnetic order
of the Ru-moments () below T_{Curie} = 133 K and
becomes superconducting at a much lower temperature T_c = 16 K. The ZF-SR
experiments indicate that the ferromagnetic phase is homogeneous on a
microscopic scale and accounts for most of the sample volume. They also suggest
that the magnetic order is not significantly modified at the onset of
superconductivity.Comment: improved version submitted to Phys. Rev.
Spin effects in transport through non-Fermi liquid quantum dots
The current-voltage characteristic of a one dimensional quantum dot connected
via tunnel barriers to interacting leads is calculated in the region of
sequential tunneling. The spin of the electrons is taken into account.
Non-Fermi liquid correlations implying spin-charge separation are assumed to be
present in the dot and in the leads. It is found that the energetic distance of
the peaks in the linear conductance shows a spin-induced parity effect at zero
temperature T. The temperature dependence of the positions of the peaks depends
on the non-Fermi liquid nature of the system. For non-symmetric tunnel barriers
negative differential conductances are predicted, which are related to the
participation in the transport of collective states in the quantum dot with
larger spins. Without spin-charge separation the negative differential
conductances do not occur. Taking into account spin relaxation destroys the
spin-induced conductance features. The possibility of observing in experiment
the predicted effects are briefly discussed.Comment: 15 pages, 16 figures, accepted for publication on Physical Review
Coexistence and competition of magnetism and superconductivity on the nanometer scale in underdoped BaFe1.89Co0.11As2
We report muon spin rotation (muSR) and infrared (IR) spectroscopy
experiments on underdoped BaFe1.89Co0.11As2 which show that bulk magnetism and
superconductivity (SC) coexist and compete on the nanometer length scale. Our
combined data reveal a bulk magnetic order, likely due to an incommensurate
spin density wave (SDW), which develops below Tmag \approx 32 K and becomes
reduced in magnitude (but not in volume) below Tc = 21.7 K. A slowly
fluctuating precursor of the SDW seems to develop alrady below the structural
transition at Ts \approx 50 K. The bulk nature of SC is established by the muSR
data which show a bulk SC vortex lattice and the IR data which reveal that the
majority of low-energy states is gapped and participates in the condensate at T
<< Tc
Macroscopic phase segregation in superconducting K0.73Fe1.67Se2 as seen by muon spin rotation and infrared spectroscopy
Using muon spin rotation (\muSR) and infrared spectroscopy we investigated
the recently discovered superconductor K0.73Fe1.67Se2 with Tc = 32 K. We show
that the combined data can be consistently described in terms of a
macroscopically phase segregated state with a matrix of ~88% volume fraction
that is insulating and strongly magnetic and inclusions with a ~12% volume
fraction which are metallic, superconducting and non-magnetic. The electronic
properties of the latter, in terms of the normal state plasma frequency and the
superconducting condensate density, appear to be similar as in other iron
selenide or arsenide superconductors.Comment: 22 pages, 8 figures. (citation list correction.
μ-Bromido-dibromido-μ-hydroxido-bisÂ[(4S)-2-halo-6-(4-isopropyl-4,5-dihydroÂoxazol-2-yl)pyridine]dicopper(II) (halo: Cl/Br = 3:1)
The crystal structure of the title complex, [Cu2Br3(OH)(C11H13Br0.5Cl1.5N2O)2], consists of two (2-halo-6-oxazolinÂyl)pyridine·CuBr units bridged by a Br atom and a hydroxide group. The CuII atoms are five-coordinate with an (N,N)BrCu(Br)(OH) distorted tetraÂgonal–pyramidal core, and relatively short contacts to the bridging atoms (Cu—μ-OH and Cu—μ-Br). There are two symmetry-independent half-molÂecules in the asymmetric unit, which differ only in the arrangement of the isopropyl group. The molÂecules are located on a twofold rotation axes
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