8,236 research outputs found
Quantum critical 5f-electrons avoid singularities in U(Ru,Rh)2Si2
We present specific heat measurements of 4% Rh-doped U(Ru,Rh)2Si2 at magnetic
fields above the proposed metamagnetic transition field Hm~34 T, revealing
striking similarities to the isotructural Ce analog CeRu2Si2, suggesting that
strongly renormalized hybridized band models apply equally well to both
systems. The vanishing bandwidths as H --> Hm are consistent with a putative
quantum critical point close to Hm. The existence of a phase transition into an
ordered phase in the vicinity of Hm for 4% Rh-doped U(Ru,Rh)2Si2, but not for
CeRu2Si2, is consistent with a stronger super-exchange in the case of the U 5-f
system, with irreversible processes at the transition revealing a strong
coupling of the 5f orbitals to the lattice, most suggestive of orbital or
electric quadrupolar order.Comment: 4 pages, 4 figure
Ferrotoroidic Moment as a Quantum Geometric Phase
We present a geometric characterization of the ferrotoroidic moment in terms
of a set of Abelian Berry phases. We also introduce a fundamental complex
quantity which provides an alternative way to calculate the ferrotoroidic
moment and its moments, and is derived from a second order tensor. This
geometric framework defines a natural computational approach for density
functional and many-body theories
Hora da colheita: hora de cuidar do seu produto e de você. Unidade móvel para sombreamento de hortaliças após a colheita.
bitstream/item/81824/1/cot-90.pd
VÃrus detectados em germoplasma vegetal introduzido no Brasil pelo laboratório de quarentena (2004-2007).
bitstream/CENARGEN/29614/1/cot172.pd
Praga Quarentenária A1. Grapevine flavescence dorée phytoplasma.
bitstream/CENARGEN/29617/1/cot173.pd
Physical approximations for the nonlinear evolution of perturbations in dark energy scenarios
The abundance and distribution of collapsed objects such as galaxy clusters
will become an important tool to investigate the nature of dark energy and dark
matter. Number counts of very massive objects are sensitive not only to the
equation of state of dark energy, which parametrizes the smooth component of
its pressure, but also to the sound speed of dark energy as well, which
determines the amount of pressure in inhomogeneous and collapsed structures.
Since the evolution of these structures must be followed well into the
nonlinear regime, and a fully relativistic framework for this regime does not
exist yet, we compare two approximate schemes: the widely used spherical
collapse model, and the pseudo-Newtonian approach. We show that both
approximation schemes convey identical equations for the density contrast, when
the pressure perturbation of dark energy is parametrized in terms of an
effective sound speed. We also make a comparison of these approximate
approaches to general relativity in the linearized regime, which lends some
support to the approximations.Comment: 15 pages, 2 figure
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