5,519 research outputs found
A perturbative approach to J mixing in f-electron systems: Application to actinide dioxides
We present a perturbative model for crystal-field calculations, which keeps
into account the possible mixing of states labelled by different quantum number
J. Analytical J-mixing results are obtained for a Hamiltonian of cubic symmetry
and used to interpret published experimental data for actinide dioxides. A
unified picture for all the considered compounds is proposed by taking into
account the scaling properties of the crystal-field potential.Comment: 16 pages + 4 figures; will appear http://prb.aps.or
A Dynamical Study of the Non-Star Forming Translucent Molecular Cloud MBM16: Evidence for Shear Driven Turbulence in the Interstellar Medium
We present the results of a velocity correlation study of the high latitude
cloud MBM16 using a fully sampled CO map, supplemented by new CO
data. We find a correlation length of 0.4 pc. This is similar in size to the
formaldehyde clumps described in our previous study. We associate this
correlated motion with coherent structures within the turbulent flow. Such
structures are generated by free shear flows. Their presence in this non-star
forming cloud indicates that kinetic energy is being supplied to the internal
turbulence by an external shear flow. Such large scale driving over long times
is a possible solution to the dissipation problem for molecular cloud
turbulence.Comment: Uses AAS aasms4.sty macros. Accepted for publication in Ap
Proposal for an Optical Test of the Einstein Equivalence Principle
The Einstein Equivalence Principle (EEP) underpins all metric theories of
gravity. Its key element is the local position invariance of non-gravitational
experiments, which entails the gravitational red-shift. Precision measurements
of the gravitational red-shift tightly bound violations of the EEP only in the
fermionic sector of the Standard Model, however recent developments of
satellite optical technologies allow for its investigation in the
electromagnetic sector. Proposals exploiting light interferometry traditionally
suffer from the first-order Doppler effect, which dominates the weak
gravitational signal necessary to test the EEP, making them unfeasible. Here,
we propose a novel scheme to test the EEP, which is based on a double
large-distance optical interferometric measurement. By manipulating the
phase-shifts detected at two locations at different gravitational potentials it
is possible to cancel-out the first-order Doppler effect and observe the
gravitational red-shift implied by the EEP. We present the detailed analysis of
the proposal within the post-Newtonian framework and the simulations of the
expected signals obtained by using two realistic satellite orbits. Our proposal
to overcome the first-order Doppler effect in optical EEP tests is feasible
with current technology.Comment: manuscript improve
Enhancement of rare-earth--transition-metal exchange interaction in PrFe probed by inelastic neutron scattering
The fundamental magnetic interactions of PrFe are studied by
inelastic neutron scattering and anisotropy field measurements. Data analysis
confirms the presence of three magnetically inequivalent sites, and reveals an
exceptionally large value of the exchange field. The unexpected importance of
-mixing effects in the description of the ground-state properties of
PrFe is evidenced, and possible applications of related compounds
are envisaged.Comment: 4 RevTeX pages, 4 EPS figures. Accepted for publication by Appl.
Phys. Lett. (will be found at http://apl.aip.org
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)
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