6,624 research outputs found
Anomalous Pinning Fields in Helical Magnets: Screening of the Quasiparticle Interaction
The spin-orbit interaction strength g_so in helical magnets determines both
the pitch wave number q and the critical field H_c1 where the helix aligns with
an external magnetic field. Within a standard Landau-Ginzburg-Wilson (LGW)
theory, a determination of g_so in MnSi and FeGe from these two observables
yields values that differ by a factor of 20. This discrepancy is remedied by
considering the fermionic theory underlying the LGW theory, and in particular
the effects of screening on the effective electron-electron interaction that
results from an exchange of helical fluctuations.Comment: 4pp, 2 fig
Phase diagram of glassy systems in an external field
We study the mean-field phase diagram of glassy systems in a field pointing
in the direction of a metastable state. We find competition among a
``magnetized'' and a ``disordered'' phase, that are separated by a coexistence
line as in ordinary first order phase transitions. The coexistence line
terminates in a critical point, which in principle can be observed in numerical
simulations of glassy models.Comment: 4 pages, 5 figure
Digestible Energy Content of Diets of Pine Voles from Different Orchard Habitat Types
In a previous study at VPI & SU, Servello (1981) developed a technique for predicting the digestible dry matter (DDM) and digestible energy (DE) of the diets of pine voles from a nutritive analysis of their stomach contents. In this nutritive analysis, developed by Goering and Van Soest (1970), feeds are divided into two major fractions: cell soluble and cell wall fractions. The cell soluble fraction is highly digestible while the cell wall (fiber) fraction varies in digestibility. It was found that the highly digestible cell soluble values of the stomach contents were the best predictor of the digestibility of the pine vole\u27s diet. The objective of the present study was to use the cell soluble values of pine vole stomach contents to determine if there were seasonal or orchard differences in the diet digestibility of pine voles captured from diverse orchard habitat types
Earth orbital teleoperator mobility system evaluation program
The proximity translation and final docking of the space teleoperator evaluation vehicle (STEV) with large mass and small mass satellites was studied. Operations that may be performed by the STEV during the shuttle experiments are approximated
Numerical study of a short-range p-spin glass model in three dimensions
In this work we study numerically a short range p-spin glass model in three
dimensions. The behaviour of the model appears to be remarkably different from
mean field predictions. In fact it shares some features typical of models with
full replica-symmetry breaking (FRSB). Nevertheless, we believe that the
transition that we study is intrinsically different from the FRSB and basically
due to non-perturbative contributions. We study both the statics and the
dynamics of the system which seem to confirm our conjectures.Comment: 20 pages, 15 figure
Transport Anomalies and Marginal Fermi-Liquid Effects at a Quantum Critical Point
The behavior of the conductivity and the density of states, as well as the
phase relaxation time, of disordered itinerant electrons across a quantum
ferromagnetic transition is discussed. It is shown that critical fluctuations
lead to anomalies in the temperature and energy dependence of the conductivity
and the tunneling density of states, respectively, that are stronger than the
usual weak-localization anomalies in a disordered Fermi liquid. This can be
used as an experimental probe of the quantum critical behavior. The energy
dependence of the phase relaxation time at criticality is shown to be that of a
marginal Fermi liquid.Comment: 4 pp., LaTeX, no figs., requires World Scientific style files
(included), Contribution to MB1
Earth orbital teleoperator system man-machine interface evaluation
The teleoperator system man-machine interface evaluation develops and implements a program to determine human performance requirements in teleoperator systems
Transport Anomalies and Marginal Fermi-Liquid Effects at a Quantum Critical Point
The conductivity and the tunneling density of states of disordered itinerant
electrons in the vicinity of a ferromagnetic transition at low temperature are
discussed. Critical fluctuations lead to nonanalytic frequency and temperature
dependences that are distinct from the usual long-time tail effects in a
disordered Fermi liquid. The crossover between these two types of behavior is
proposed as an experimental check of recent theories of the quantum
ferromagnetic critical behavior. In addition, the quasiparticle properties at
criticality are shown to be those of a marginal Fermi liquid.Comment: 4pp., REVTeX, no figs, final version as publishe
Quantum critical behavior in disordered itinerant ferromagnets: Logarithmic corrections to scaling
The quantum critical behavior of disordered itinerant ferromagnets is
determined exactly by solving a recently developed effective field theory. It
is shown that there are logarithmic corrections to a previous calculation of
the critical behavior, and that the exact critical behavior coincides with that
found earlier for a phase transition of undetermined nature in disordered
interacting electron systems. This confirms a previous suggestion that the
unspecified transition should be identified with the ferromagnetic transition.
The behavior of the conductivity, the tunneling density of states, and the
phase and quasiparticle relaxation rates across the ferromagnetic transition is
also calculated.Comment: 15pp., REVTeX, 8 eps figs, final version as publishe
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