1,133 research outputs found
Reply to ``Comment on `Hole-burning experiments within glassy models with infinite range interactions' ''
This is a reply to the comments by Richter and Chamberlin, and Diezemann and
Bohmer to our paper (Phys. Rev. Lett. 85, 3448 (2000)). As further evidence for
the claims in this Letter, we here reproduce the nonlinear spectral
hole-burning experimental protocol in an equilibrated fully connected
spin-glass model and we exhibit frequency selectivity, together with a shift in
the base of the spectral hole.Comment: 1 page, two figures, to appear in Phys. Rev. Let
Hole-burning experiments within solvable glassy models
We reproduce the results of non-resonant spectral hole-burning experiments
with fully-connected (equivalently infinite-dimensional) glassy models that are
generalizations of the mode-coupling approach to nonequilibrium situations. We
show that an ac-field modifies the integrated linear response and the
correlation function in a way that depends on the amplitude and frequency of
the pumping field. We study the effect of the waiting and recovery-times and
the number of oscillations applied. This calculation will help descriminating
which results can and which cannot be attributed to dynamic heterogeneities in
real systems.Comment: 4 pages, 8 figures, RevTe
Signatures of Spin Glass Freezing in NiO Nanoparticles
We present a detailed study of the magnetic properties of sol-gel prepared
nickel oxide nanoparticles of different sizes. We report various measurements
such as frequency, field and temperature dependence of ac susceptibility,
temperature and field dependence of dc magnetization and time decay of
thermoremanent magnetization. Our results and analysis show that the system
behaves as a spin glass.Comment: 8 pages, 9 figure
Theory of Thermodynamic Magnetic Oscillations in Quasi-One-Dimensional Conductors
The second order correction to free energy due to the interaction between
electrons is calculated for a quasi-one-dimensional conductor exposed to a
magnetic field perpendicular to the chains. It is found that specific heat,
magnetization and torque oscillate when the magnetic field is rotated in the
plane perpendicular to the chains or when the magnitude of magnetic filed is
changed. This new mechanism of thermodynamic magnetic oscillations in metals,
which is not related to the presence of any closed electron orbits, is applied
to explain behavior of the organic conductor (TMTSF)ClO.Comment: 11 pages + 5 figures (included
Nulling interferometry: performance comparison between Antarctica and other ground-based sites
Detecting the presence of circumstellar dust around nearby solar-type main
sequence stars is an important pre-requisite for the design of future
life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet
Finder (TPF). The high Antarctic plateau may provide appropriate conditions to
perform such a survey from the ground. We investigate the performance of a
nulling interferometer optimised for the detection of exozodiacal discs at Dome
C, on the high Antarctic plateau, and compare it to the expected performance of
similar instruments at temperate sites. Based on the currently available
measurements of the turbulence characteristics at Dome C, we adapt the GENIEsim
software (Absil et al. 2006, A&A 448) to simulate the performance of a nulling
interferometer on the high Antarctic plateau. To feed a realistic instrumental
configuration into the simulator, we propose a conceptual design for ALADDIN,
the Antarctic L-band Astrophysics Discovery Demonstrator for Interferometric
Nulling. We assume that this instrument can be placed above the 30-m high
boundary layer, where most of the atmospheric turbulence originates. We show
that an optimised nulling interferometer operating on a pair of 1-m class
telescopes located 30 m above the ground could achieve a better sensitivity
than a similar instrument working with two 8-m class telescopes at a temperate
site such as Cerro Paranal. The detection of circumstellar discs about 20 times
as dense as our local zodiacal cloud seems within reach for typical Darwin/TPF
targets in a integration time of a few hours. Moreover, the exceptional
turbulence conditions significantly relax the requirements on real-time control
loops, which has favourable consequences on the feasibility of the nulling
instrument.Comment: 10 pages, accepted for publication in A&
Universal Power Law in the Noise from a Crumpled Elastic Sheet
Using high-resolution digital recordings, we study the crackling sound
emitted from crumpled sheets of mylar as they are strained. These sheets
possess many of the qualitative features of traditional disordered systems
including frustration and discrete memory. The sound can be resolved into
discrete clicks, emitted during rapid changes in the rough conformation of the
sheet. Observed click energies range over six orders of magnitude. The measured
energy autocorrelation function for the sound is consistent with a stretched
exponential C(t) ~ exp(-(t/T)^{b}) with b = .35. The probability distribution
of click energies has a power law regime p(E) ~ E^{-a} where a = 1. We find the
same power law for a variety of sheet sizes and materials, suggesting that this
p(E) is universal.Comment: 5 pages (revtex), 10 uuencoded postscript figures appended, html
version at http://rainbow.uchicago.edu/~krame
Validity of the second law in nonextensive quantum thermodynamics
The second law of thermodynamics in nonextensive statistical mechanics is
discussed in the quantum regime. Making use of the convexity property of the
generalized relative entropy associated with the Tsallis entropy indexed by q,
Clausius' inequality is shown to hold in the range of q between zero and two.
This restriction on the range of the entropic index, q, is purely quantum
mechanical and there exists no upper bound of q for validity of the second law
in classical theory.Comment: 12 pages, no figure
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