25,298 research outputs found
Heterogeneous spin state in the field-induced phase of volborthite as seen via 51V nuclear magnetic resonance
We report results of 51V NMR in the field-induced phase of volborthite
Cu3V2O7(OH)dot2H2O, a spin-1/2 antiferromagnet on a distorted kagome lattice.
In magnetic fields above 4.5 T, two types of V sites with different spin-echo
decay rates are observed. The hyperfine field at the fast decaying sites has a
distribution, while it is more homogeneous at the slowly decaying sites. Our
results indicate a heterogeneous state consisting of two spatially alternating
Cu spin systems, one of which exhibits anomalous spin fluctuations contrasting
with the other showing a conventional static order.Comment: 5 pages, 4 figure
Spin-1/2 Triangular Lattice with Orbital Degeneracy in a Metallic Oxide Ag2NiO2
A novel metallic and magnetic transition metal oxide Ag2NiO2 is studied by
means of resistivity, magnetic susceptibility, specific heat and X-ray
diffraction. The crystal structure is characterized by alternating stacking of
a Ni3+O2 layer and a (Ag2)+ layer, the former realizing a spin-1/2 triangular
lattice with eg orbital degeneracy and the latter providing itinerant
electrons. It is found that the NiO2 layer exhibits orbital ordering at Ts =
260 K and antiferromagnetic spin ordering at TN = 56 K. Moreover, a moderately
large mass enhancement is found for the itinerant electrons, suggesting a
significant contribution from the nearly localized Ni 3d state to the Ag 5s
state that forms a broad band.Comment: 9 pages, 5 figures, to be published in Rapid Communications, Phys.
Rev.
Novel Quantum Criticality in CeRuSi near Absolute Zero Observed by Thermal Expansion and Magnetostriction
We report linear thermal expansion and magnetostriction measurements for
CeRuSi in magnetic fields up to 52.6 mT and at temperatures down to 1
mK. At high temperatures, this compound showed Landau-Fermi-liquid behavior:
The linear thermal expansion coefficient and the magnetostriction coefficient
were proportional to the temperature and magnetic field, respectively. In
contrast, a pronounced non-Fermi-liquid effect was found below 50 mK. The
negative contribution of thermal expansion and magnetostriction suggests the
existence of an additional quantum critical point
Probing the twist-3 multi-gluon correlation functions by pp \to DX
We study the single spin asymmetry (SSA) for the D-meson production
in the collision, , in the framework of the collinear
factorization. Since the charm quark is mainly produced through the
-pair creation from the gluon-fusion process, this is an ideal
process to probe the twist-3 triple-gluon correlation functions in the
polarized nucleon. We derive the corresponding cross section formula for the
contribution of the triple-gluon correlation function to in , applying the method developed for in our
previous study. As in the case of , our result differs from
a previous study in the literature. We will also present a simple estimate of
the triple-gluon correlation functions based on the preliminary data on
by RHIC.Comment: to appear in the proceedings of the 19th International Spin Physics
Symposium (Spin2010), Sept.27 - Oct.2, 2010, Juelich, Germany, 5 pages, 2
figure
Tuning the spin dynamics of kagome systems
Despite the conceptional importance of realizing spin liquids in solid states
only few compounds are known. On the other side the effect of lattice
distortions and anisotropies on the magnetic exchange topology and the
fluctuation spectrum are an interesting problem. We compare the excitation
spectra of the two s=1/2 kagome lattice compounds volborthite and vesignieite
using Raman scattering. We demonstrate that even small modifications of the
crystal structure may have a huge effect on the phonon spectrum and low
temperature properties.Comment: 3 pages, 2 figure
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