88 research outputs found
Structural behavior of PbBiSrLaCuO for 0<y<0.53
In the Bi cuprates, the presence of a near 15 superstructure is well
known. Usually, this superstructure is suppressed by the substitution of lead,
but there have been reports of a phase separation in so called {\alpha} and
{\beta} phases. This paper shows in high detail time how and why the phase
separation develops and what happens to the quasi-15 superstructure
upon lead substitution. For this purpose, the lanthanum- and lead-substituted
single-layered superconductor BiSrCuO has been
investigated by scanning tunneling microscopy and low-energy electron
diffraction. The La content was kept constant at slightly under-doped
concentration while the Pb content was changed systematically. Thermodynamic
considerations show that a phase mixture of {\alpha} and {\beta} phases is
inevitable.Comment: 17 pages, 4 figure
Atualidades e desafios nas fases de crescimento e terminação: 1) sistemas de alimentação.
Projeto: 11.11.11.111
Novos desenvolvimentos na nutrição dos leitões nas fases de crescimento e terminação.
Projeto/Plano de Ação: 03.07.05.019
Uso de permeado spray-dried (PERLAC 850®) produzido a partir de soro de leite doce em substituição ao soro de leite e à lactose pura em dietas de leitões recém-desmamados.
bitstream/item/78977/1/Comunicado-507.pdfProjeto/Plano de Ação: 03.12.01.025
Spectroscopic signatures of a bandwidth-controlled Mott transition at the surface of 1T-TaSe
High-resolution angle-resolved photoemission (ARPES) data show that a
metal-insulator Mott transition occurs at the surface of the quasi-two
dimensional compound TaSe. The transition is driven by the narrowing of the
Ta band induced by a temperature-dependent modulation of the atomic
positions. A dynamical mean-field theory calculation of the spectral function
of the half-filled Hubbard model captures the main qualitative feature of the
data, namely the rapid transfer of spectral weight from the observed
quasiparticle peak at the Fermi surface to the Hubbard bands, as the
correlation gap opens up.Comment: 4 pages, 4 figures; one modified figure, added referenc
Luttinger liquid phenomenology and angle resolved photoemission for single layer \chem{Bi_2Sr_{2-x}La_xCuO_{6+\delta}} high--temperature superconductor
Recently observed splitting in angular resolved photoemission spectroscopy
(ARPES) on \chem{Bi_2Sr_{2-x}La_xCuO_{6+\delta}} high--temperature
superconductor (Janowitz C. {\it et al.}, {\it Europhys. Lett.}, {\bf 60}
(2002) 615) is interpreted within the phenomenological Luttinger--liquid
framework, in which both the non--Fermi liquid scaling exponent of the spectral
function and the spin--charge separation are introduced. The anomalous Green
function with adjustable parameters fits very well to the Fermi edge and the
low--energy part of ARPES along the line in the Brillouin zone. In
contrast to one--dimensional models with Luttinger--liquid behavior we find
that both the anomalous scaling and the parameter describing
the spin--charge separation are momentum dependent. The higher--energy part of
the spectra is not accounted for by this simple Luttinger--liquid form of the
Green function. In this energy regime additional scattering processes are
plausible to produce the experimentally observed wide incoherent background,
which diminishes as the inverse of the energy.Comment: 7 pages, 3 figures, EPL styl
Suplementação de alimento lácteo lÃquido para leitões recém-nascidos.
bitstream/item/93620/1/edit6977.pd
Limited Angle C-Arm Tomography and Segmentation for Guidance of Atrial Fibrillation Ablation Procedures
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