45,319 research outputs found
Transport through a single Anderson impurity coupled to one normal and two superconducting leads
We study the interplay between the Kondo and Andreev-Josephson effects in a
quantum dot coupled to one normal and two superconducting (SC) leads. In the
large gap limit, the low-energy states of this system can be described exactly
by a local Fermi liquid for the interacting Bogoliubov particles. The phase
shift and the renormalized parameters for the Bogoliubov particles vary
depending on the Josephson phase between the two SC leads. We explore the
precise features of a crossover that occurs between the Kondo singlet and local
Cooper-pairing states as the Josephson phase varies, using the numerical
renormalization group approach.Comment: 4 pages, 4 figures, contribution to SCES 201
Magnetic-Field Induced Gap in One-Dimensional Antiferromagnet KCuGaF
Magnetic susceptibility and specific heat measurements in magnetic fields
were performed on an one-dimensional antiferromagnet KCuGaF.
Exchange interaction was evaluated as K. However, no
magnetic ordering was observed down to 0.46 K. It was found that an applied
magnetic field induces a staggered magnetic susceptibility obeying the Curie
law and an excitation gap, both of which should be attributed to the
antisymmetric interaction of the Dzyaloshinsky-Moriya type and/or the staggered
-tensor. With increasing magnetic field , the gap increases almost in
proportion to .Comment: Submitted to Proceedings of Research in High Magnetic Fiel
Escape of black holes from the brane
TeV-scale gravity theories allow the possibility of producing small black
holes at energies that soon will be explored at the LHC or at the Auger
observatory. One of the expected signatures is the detection of Hawking
radiation, that might eventually terminate if the black hole, once perturbed,
leaves the brane. Here, we study how the `black hole plus brane' system evolves
once the black hole is given an initial velocity, that mimics, for instance,
the recoil due to the emission of a graviton. The results of our dynamical
analysis show that the brane bends around the black hole, suggesting that the
black hole eventually escapes into the extra dimensions once two portions of
the brane come in contact and reconnect. This gives a dynamical mechanism for
the creation of baby branes.Comment: 4 pages, 6 figure
Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method
In-plane thermal conductivity of the thermoelectric layered cobalt oxides has
been measured using the Harman method, in which thermal conductivity is
obtained from temperature gradient induced by applied current. We have found
that the charge reservoir block (the block other than the CoO block)
dominates the thermal conduction, where a nano-block integration concept is
effective for material design. We have further found that the thermal
conductivity shows a small but finite in-plane anisotropy between and
axes, which can be ascribed to the misfit structure.Comment: 4 pages, 4 figures, J. Appl. Phys. (scheduled on July 1, 2004
Constraints on Braneworld Gravity Models from a Kinematic Limit on the Age of the Black Hole XTE J1118+480
In braneworld gravity models with a finite AdS curvature in the extra
dimension, the AdS/CFT correspondence leads to a prediction for the lifetime of
astrophysical black holes that is significantly smaller than the Hubble time,
for asymptotic curvatures that are consistent with current experiments. Using
the recent measurements of the position, three-dimensional spatial velocity,
and mass of the black hole XTE J1118+480, I calculate a lower limit on its
kinematic age of 11 Myr (95% confidence). This translates into an upper limit
for the asymptotic AdS curvature in the extra dimensions of 0.08 mm, which
significantly improves the limit obtained by table-top experiments of sub-mm
gravity.Comment: 4 pages, to appear in the Physical Review Letter
Semi-relativistic approximation to gravitational radiation from encounters with nonspinning black holes
The capture of compact bodies by black holes in galactic nuclei is an
important prospective source for low frequency gravitational wave detectors,
such as the planned Laser Interferometer Space Antenna. This paper calculates,
using a semirelativistic approximation, the total energy and angular momentum
lost to gravitational radiation by compact bodies on very high eccentricity
orbits passing close to a supermassive, nonspinning black hole; these
quantities determine the characteristics of the orbital evolution necessary to
estimate the capture rate. The semirelativistic approximation improves upon
treatments which use orbits at Newtonian-order and quadrupolar radiation
emission, and matches well onto accurate Teukolsky simulations for low
eccentricity orbits. Formulae are presented for the semirelativistic energy and
angular momentum fluxes as a function of general orbital parameters.Comment: 27 pages, 12 figures; v2: revised manuscript includes small changes
to make paper consistent with published version; v3: a statement about how to
generalise our results to hyperbolic orbits was incorrect, new version
includes published erratum as an appendi
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