1,876 research outputs found
Incommensurate antiferromagnetic fluctuations in single-crystalline LiFeAs studied by inelastic neutron scattering
We present an inelastic neutron scattering study on single-crystalline LiFeAs
devoted to the characterization of the incommensurate antiferromagnetic
fluctuations at . Time-of-flight
measurements show the presence of these magnetic fluctuations up to an energy
transfer of 60 meV, while polarized neutrons in combination with longitudinal
polarization analysis on a triple-axis spectrometer prove the pure magnetic
origin of this signal. The normalization of the magnetic scattering to an
absolute scale yields that magnetic fluctuations in LiFeAs are by a factor
eight weaker than the resonance signal in nearly optimally Co-doped
BaFeAs, although a factor two is recovered due to the split peaks owing
to the incommensurability. The longitudinal polarization analysis indicates
weak spin space anisotropy with slightly stronger out-of-plane component
between 6 and 12 meV. Furthermore, our data suggest a fine structure of the
magnetic signal most likely arising from superposing nesting vectors.Comment: 9 pages, 8 figure
Scheme Independence of
We work with two general factorization schemes in order to explore the
consequences of imposing scheme independence on . We see that
although the light quark sector is indifferent to the choice of a particular
scheme, the extension of the calculations to the heavy quark sector indicates
that a scheme like the is preferable.Comment: 11 pages, 2 figures. To appear in the Brief Reports of Phys. Rev.
Two Ising-like magnetic excitations in a single-layer cuprate superconductor
There exists increasing evidence that the phase diagram of the
high-transition temperature (Tc) cuprate superconductors is controlled by a
quantum critical point. One distinct theoretical proposal is that, with
decreasing hole-carrier concentration, a transition occurs to an ordered state
with two circulating orbital currents per CuO2 square. Below the 'pseudogap'
temperature T* (T* > Tc), the theory predicts a discrete order parameter and
two weakly-dispersive magnetic excitations in structurally simple compounds
that should be measurable by neutron scattering. Indeed, novel magnetic order
and one such excitation were recently observed. Here, we demonstrate for
tetragonal HgBa2CuO4+d the existence of a second excitation with local
character, consistent with the theory. The excitations mix with conventional
antiferromagnetic fluctuations, which points toward a unifying picture of
magnetism in the cuprates that will likely require a multi-band description.Comment: Including supplementary informatio
Inoculação de bactérias fixadoras de nitrogênio em arroz de sequeiro (Oryza sativa): respostas fisiológicas em estudos in vitro.
Este estudo determinou as respostas fisiológicas de 10 variedades de arroz de sequeiro (Oryza sativa L.) inoculação utilizando bactérias fixadoras de nitrogênio em ensaios in vitro
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