944 research outputs found
Observation of a half step magnetization in the {Cu-3}-type triangular spin ring
We report pulsed field magnetization and ESR experiments on a {Cu-3} nanomagnet, where antiferromagnetically coupled Cu2+ (S=1/2) ions form a slightly distorted triangle. The remarkable feature is the observation of a half step magnetization, hysteresis loops, and an asymmetric magnetization between a positive and a negative field in a fast sweeping external field. This is attributed to an adiabatic change of magnetization. The energy levels determined by ESR unveil that the different mixing nature of a spin chirality of a total S=1/2 Kramers doublet by virtue of Dzyaloshinskii-Moriya interactions is decisive for inducing half step magnetization.</p
Interplay of electronic correlations and lattice instabilities in BaVS3
The quasi-one-dimensional metallic system BaVS3 with a metal-insulator
transition at T_MI=70 K shows large changes of the optical phonon spectrum, a
central peak, and an electronic Raman scattering continuum that evolve in a
three-step process. Motivated by the observation of a strongly fluctuating
precursor state at high temperatures and orbital ordering and a charge gap at
low temperatures we suggest a concerted action of the orbital, electronic, and
lattice subsystems dominated by electronic correlations.Comment: 4 pages, 4 figure
Fire Resistance on Bearing Wall Using Steel & Gypsum
The conventional loadbearing wall systems generally used in Korea are composed of concrete and brick. Which materials have many defaults like long-term construction period and cost increase. Recently in us, a rapid increase in the usage of cold-formed steel section in housing and commercial building construction can widely be seen. The loadbearing wall assembly composed of light gauge-steel and gypsum board can preferably be applied to residential and commercial building of 5 stories or below. In order that light-gauge steel framing can be prevalently introduced in our domestic housing market, the wall assembly must have sufficient fire-resistant performance. Fire-resistant tests were conducted for the load bearing wall specimens of 7.2mĂÂČ in size and fire tests were carried out on load-bearing wall systems by method of loading condition and unloading condition in full size of specimens in order to certify the fire-resistance properties. Through test results, the temperature slopes of each material such as steel, insulation and gypsum board were obtained, along with the vertical and horizontal deflection of specimens
Doping effects on charge density instability in non-centrosymmetric PbxTaSe2
We report on the investigation of vibrational and electronic properties of
the Pb doped dichalcogenide PbxTaSe2 using Raman scattering experiments. We
observe a marked variation of the main vibrational modes with Pb concentration
x. The concentration dependence of the vibrational modes resembles the
dependence of the vibrational modes in TaSe2 on the number of crystallographic
layers along the c axis direction [1]. The temperature and polarization
dependence of Raman spectra of PbxTaSe2 revealed additional broad modes in the
low frequency regime which are discussed in context of remnant charge density
wave, induced disorder, or PbSe phase formed in the interface of Pb and TaSe2
layers.Comment: 14 page
Anomalous frequency and intensity scaling of collective and local modes in a coupled spin tetrahedron system
We report on the magnetic excitation spectrum of the coupled spin tetrahedral
system CuTeOCl using Raman scattering on single
crystals. The transition to an ordered state at T=18.2 K evidenced
from thermodynamic data leads to the evolution of distinct low-energy magnetic
excitations superimposed by a broad maximum. These modes are ascribed to
magnons with different degree of localization and a two-magnon continuum. Two
of the modes develop a substantial energy shift with decreasing temperature
similar to the order parameter of other Neel ordered systems. The other two
modes show only a negligible temperature dependence and dissolve above the
ordering temperature in a continuum of excitations at finite energies. These
observations point to a delicate interplay of magnetic inter- and
intra-tetrahedra degrees of freedom and an importance of singlet fluctuations
in describing a spin dynamics.Comment: 7pages, 6figures, 1tabl
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Unusual spin pseudogap behavior in the spin web lattice Cu3TeO6 probed by 125Te nuclear magnetic resonance
We present a 125Te nuclear magnetic resonance (NMR) study in the three-dimensional spin web lattice Cu3TeO6 which harbors topological magnons. The 125Te NMR spectra and the Knight-shift K as a function of temperature show a drastic change at TSâŒ40K much lower than the NĂ©el ordering temperature TNâŒ61K, providing evidence for the first-order structural phase transition within the magnetically ordered state. Most remarkably, the temperature dependence of the spin-lattice relaxation rate Tâ11 unravels spin-gap-like magnetic excitations, which sharply sets in at TââŒ75K, the temperature well above TN. The spin-gap behavior may be understood by weakly dispersive optical magnon branches of high-energy spin excitations originating from the unique corner-sharing Cu hexagon spin-1/2 network with low coordination number
Transport of Phosphate by Renal Brush Border Membrane Vesicle (BBMV) during Development - Role of the Growth Hormone-
It is well documented that plasma concentrations of Pi (inorganic phosphorus)
are higher in developing subjects than in adults. In a previous study, we demonstrated
that the Vmax (capacity) of the Na-Pi cotransport mechanism of the renal brush
border membrane vesicles was higher in immature than mature rats.
In this study, we evaluated the role of a growth hormone in the maintenance of a
higher Vmax observed in immature rats.
In mature rats, serum Pi, and the tubular reabsorption of Pi (TRPi) increased in the
growth hormone treated animals. On the other hand, those values were not changed
by growth hormone treatment in immature rats.
In kinetic analysis, the Km (affinity) values were not different between the control
(growth hormone-untreated) and growth hormone-treated renal brush border membrane
vesicles in both immature and mature rats. The Vmax of the immature rats also was
not changed by growth hormone treatment. On the contrary, Vmax increased significantly
in the growth-hormone treated than the control mature rats.
With the above findings, it seems that immature rats reabsorb Pi maximally even
in the control state, and it is likely that a growth hormone is responsible for the phenomenon
Coupled spin-lattice fluctuations in a compound with orbital degrees of freedom: the Cr based dimer system Sr3Cr2O8
We report on an extended fluctuation regime in the spin dimer system Sr3Cr2O8
based on anomalies in Raman active phonons and magnetic scattering. The
compound has two characteristic temperatures, TS = 275 K, related to a
Jahn-Teller transition with structural distortions and orbital ordering and a
second, T*= 150 K, which is due to further changes in the orbital sector. Below
TS quasielastic scattering marks strong fluctuations and in addition phonon
anomalies are observed. For temperatures below T* we observe an exponential
decrease of one phonon linewidth and determine a gap of the orbital
excitations. At low temperatures the observation of two- and three-magnon
scattering allows the determination of the spin excitation gap.Comment: 7 pages, 4 figures, 1 tabl
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