1,773 research outputs found
Uniaxial magnetocrystalline anisotropy in
is a paramagnetic metal and since its low temperature
resistivity is described by with , it
is also considered a non-Fermi liquid (NFL) metal. We have performed extensive
magnetoresistance and Hall effect measurements of untwinned epitaxial films of
. These measurements reveal that exhibits
uniaxial magnetocrystalline anisotropy. In addition, the low-temperature NFL
behavior is most effectively suppressed when a magnetic field is applied along
the easy axis, suggesting that critical spin fluctuations, possibly due to
proximity of a quantum critical phase transition, are related to the NFL
behavior.Comment: 7 figure
Strong and Weak Optimizations in Classical and Quantum Models of Stochastic Processes
Among the predictive hidden Markov models that describe a given stochastic
process, the {\epsilon}-machine is strongly minimal in that it minimizes every
R\'enyi-based memory measure. Quantum models can be smaller still. In contrast
with the {\epsilon}-machine's unique role in the classical setting, however,
among the class of processes described by pure-state hidden quantum Markov
models, there are those for which there does not exist any strongly minimal
model. Quantum memory optimization then depends on which memory measure best
matches a given problem circumstance.Comment: 14 pages, 14 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/uemum.ht
A Statistical Measure of Complexity
A measure of complexity based on a probabilistic description of physical
systems is proposed. This measure incorporates the main features of the
intuitive notion of such a magnitude. It can be applied to many physical
situations and to different descriptions of a given system. Moreover, the
calculation of its value does not require a considerable computational effort
in many cases of physical interest.Comment: 8 pages, 0 figure
Resurgence of oscillation in coupled oscillators under delayed cyclic interaction
This paper investigates the emergence of amplitude death and revival of
oscillations from the suppression states in a system of coupled dynamical units
interacting through delayed cyclic mode. In order to resurrect the oscillation
from amplitude death state, we introduce asymmetry and feedback parameter in
the cyclic coupling forms as a result of which the death region shrinks due to
higher asymmetry and lower feedback parameter values for coupled oscillatory
systems. Some analytical conditions are derived for amplitude death and revival
of oscillations in two coupled limit cycle oscillators and corresponding
numerical simulations confirm the obtained theoretical results. We also report
that the death state and revival of oscillations from quenched state are
possible in the network of identical coupled oscillators. The proposed
mechanism has also been examined using chaotic Lorenz oscillator.Comment: 16 pages, 13 figure
Thermoelectric enhancement in PbTe with K, Na co-doping from tuning the interaction of the light and heavy hole valence bands
The effect of K and K-Na substitution for Pb atoms in the rock salt lattice
of PbTe was investigated to test a hypothesis for development of resonant
states in the valence band that may enhance the thermoelectric power. We
combined high temperature Hall-effect, electrical conductivity and thermal
conductivity measurements to show that K-Na co-doping do not form resonance
states but2 can control the energy difference of the maxima of the two primary
valence sub-bands in PbTe. This leads to an enhanced interband interaction with
rising temperature and a significant rise in the thermoelectric figure of merit
of p-type PbTe. The experimental data can be explained by a combination of a
single and two-band model for the valence band of PbTe depending on hole
density that varies in the range of 1-15 x 10^19 cm^-3.Comment: 8 figure
Interplay between Kondo suppression and Lifshitz transitions in YbRhSi at high magnetic fields
We investigate the magnetic field dependent thermopower, thermal
conductivity, resistivity and Hall effect in the heavy fermion metal YbRh2Si2.
In contrast to reports on thermodynamic measurements, we find in total three
transitions at high fields, rather than a single one at 10 T. Using the Mott
formula together with renormalized band calculations, we identify Lifshitz
transitions as their origin. The predictions of the calculations show that all
experimental results rely on an interplay of a smooth suppression of the Kondo
effect and the spin splitting of the flat hybridized bands.Comment: 5 pages, 4 figure
How speed of sound measurements could bring constraints on the composition of Titan's seas
The hydrocarbons seas of Titan, discovered by Cassini/Huygens mission are
among the most mysterious and interesting features of this moon. In the future,
a possible dedicated planetary probe, will certainly measure the speed of sound
in this cryogenic liquid, as it was planned in the case of a Huygens landing
into a sea. Previous theoretical studies of such acoustic measurements were
based on rather simple models, leading in some cases to unphysical situations.
Employed in a vast body of chemical engineering works, the state of the art
PC-SAFT model has been recently introduced in studies aimed at Titan. Here, I
revisit the issue of the speed of sound in Titan's liquids, in the light of
this theory. I describe, in detail, the derivation of the speed of sound from
the chosen equation of state and the potential limitations of the approach. To
make estimations of the composition of a ternary liquid mixture N2:CH4:C2H6
from speed of sound measurements an original inversion algorithm is proposed.
It is shown that 50 measures between 90 K and 100 K are enough to ensure an
accuracy of the derived compositions better than 10%. The influence of the
possible presence of propane is also investigated.Comment: 7 pages, 5 figures, accepted in MNRA
- …