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

Phase diagram and spin Hamiltonian of weakly-coupled anisotropic S=1/2 chains in CuCl2*2((CD3)2SO)

Field-dependent specific heat and neutron scattering measurements were used to explore the antiferromagnetic S=1/2 chain compound CuCl2 * 2((CD3)2SO). At zero field the system acquires magnetic long-range order below TN=0.93K with an ordered moment of 0.44muB. An external field along the b-axis strengthens the zero-field magnetic order, while fields along the a- and c-axes lead to a collapse of the exchange stabilized order at mu0 Hc=6T and mu0 Hc=3.5T, respectively (for T=0.65K) and the formation of an energy gap in the excitation spectrum. We relate the field-induced gap to the presence of a staggered g-tensor and Dzyaloshinskii-Moriya interactions, which lead to effective staggered fields for magnetic fields applied along the a- and c-axes. Competition between anisotropy, inter-chain interactions and staggered fields leads to a succession of three phases as a function of field applied along the c-axis. For fields greater than mu0 Hc, we find a magnetic structure that reflects the symmetry of the staggered fields. The critical exponent, beta, of the temperature driven phase transitions are indistinguishable from those of the three-dimensional Heisenberg magnet, while measurements for transitions driven by quantum fluctuations produce larger values of beta.Comment: revtex 12 pages, 11 figure

Short-term tuna fishing community: the dwellings in the 30s and 60s

This article describes the dwellings of a short-term tuna fishing community settled in Faro beach, Algarve, Portugal, between the 30s and 60s, that already disappeared. It is related how the change from the reed houses to the wooden sheds took place and how was the day-by-day of fishermen and their families during the tuna fishing season, from March to June. In the course of this research it was discovered that such fishing community took place in Faro beach for long decades, involved a large group of fishermen and their families that lived there, in a structured way. The main results we hope to achieve are the general awareness of this heritage and its dissemination. This research was based on documentary analysis, photographic and bibliographic research but, more importantly, interviews with people involved in this art, that still remains. During the development of this research, limitations were found due to the scarcity of available information and to the advanced age of the people involved, now with around 90 years old. That's why there's an urgency to make an adequate registration and disclosure of this heritage. This paper is original because there aren't many works about this theme under this point of view, taking Faro beach as object of study. As a vernacular heritage, it must be valued, so, publishing such work would influence the society in general, but primarily, the region's society, to alert them to a value that has been forgotten and, at the same time, clarify the future generations, helping to preserve the collective memory of a professional art that disappeared from the Algarve.info:eu-repo/semantics/publishedVersio

Vírus detectados em germoplasma vegetal introduzido no Brasil pelo laboratório de quarentena (2004-2007).

bitstream/CENARGEN/29614/1/cot172.pd

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

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