2,415 research outputs found
Unexpected phase locking of magnetic fluctuations in the multi-k magnet USb
The spin waves in the multi-k antiferromagnet USb soften and become quasielastic well below the antiferromagnetic ordering temperature TN. This occurs without a magnetic or structural transition. It has been suggested that this change is in fact due to dephasing of the different multi-k components: a switch from 3-k to 1-k behavior. In this work, we use inelastic neutron scattering with tridirectional polarization analysis to probe the quasielastic magnetic excitations and reveal that the 3-k structure does not dephase. More surprisingly, the paramagnetic correlations also maintain the same clear phase correlations well above TN (up to at least 1.4TN)
Magnetic Excitations in NpCoGa5
We report the results of inelastic neutron scattering experiments on
NpCoGa, an isostructural analogue of the PuCoGa superconductor. Two
energy scales characterize the magnetic response in the antiferromagnetic
phase. One is related to a non-dispersive excitation between two crystal field
levels. The other at lower energies corresponds to dispersive fluctuations
emanating from the magnetic zone center. The fluctuations persist in the
paramagnetic phase also, although weaker in intensity. This supports the
possibility that magnetic fluctuations are present in PuCoGa, where
unconventional d-wave superconductivity is achieved in the absence of magnetic
order.Comment: 4 pages, 5 figure
CH radio emission from heiles cloud 2 as a tracer of molecular cloud evolution
A mapping observation of the -type doubling transition (3.3
GHz) of CH has been conducted toward Heiles Cloud 2 (HCL2) in the Taurus
molecular cloud complex to reveal its molecular cloud-scale distribution. The
observations were carried out with the Effelsberg 100 m telescope. The CH
emission is found to be extended over the whole region of HCL2. It is brighter
in the southeastern part, which encloses the TMC-1 cyanopolyyne peak than in
the northwestern part. Its distribution extends continuously from the peak of
the neutral carbon emission (CI peak) to the TMC-1 ridge, as if it were
connecting the distributions of the [C I] and CO emissions. Since CH is
an intermediate in gas-phase chemical reactions from C to CO, its emission
should trace the transition region. The above distribution of the CH emission
is consistent with this chemical behavior. Since the CH abundance is subject to
the chemical evolutionary effect, the CH column density in HCL2 no longer
follows a linear correlation wit the H column density reported for diffuse
and translucent clouds. More importantly, the CH line profile is found to be
composed of the narrow and broad components. Although the broad component is
dominant around the CI peak, the narrow component appears in the TMC-1 ridge
and dense core regions such as L1527 and TMC-1A. This trend seems to reflect a
narrowing of the line width during the formation of dense cores. These results
suggest that the 3.3 GHz CH line is a useful tool for tracing the chemical and
physical evolution of molecular clouds.Comment: 8 page
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