3,865 research outputs found
Computation over galois fields using shiftregisters
This paper presents a technique for readily determining the shiftregister which multiplies by a given element of GF(2m)}, or which raises a given element of GF(2m)} to a given power. A matrix (called a connection matrix) is derived from a primitive polynomial and is corresponded to a particular shiftregister. The nth power of the matrix corresponds to the shiftregister which multiplies by Xn. Examples are presented to illustrate the application of the technique
Anomalous quasiparticle transport in the superconducting state of CeCoIn5
We report on a study of thermal Hall conductivity k_xy in the superconducting
state of CeCoIn_5. The scaling relation and the density of states of the
delocalized quasiparticles, both obtained from k_xy, are consistent with d-wave
superconducting symmetry. The onset of superconductivity is accompanied by a
steep increase in the thermal Hall angle, pointing to a striking enhancement in
the quasiparticle mean free path. This enhancement is drastically suppressed in
a very weak magnetic field. These results highlight that CeCoIn_5 is unique
among superconductors. A small Fermi energy, a large superconducting gap, a
short coherence length, and a long mean free path all indicate that CeCoIn_5 is
clearly in the superclean regime (E_F/Delta<<l/xi), in which peculiar vortex
state is expected.Comment: 5 pages, 5 figure
Superconducting Gap Function in Antiferromagnetic Heavy-Fermion UPd_2Al_3 Probed by Angle Resolved Magnetothermal Transport Measurements
The superconducting gap structure of heavy fermion UPd_2Al_3, in which
unconventional superconductivity coexists with antiferromagnetic (AF) order
with atomic size local moments, was investigated by the thermal conductivity
measurements in a magnetic field rotating in various directions relative to the
crystal axes. The results provide strong evidence that the gap function
\Delta(k) has a single line node orthogonal to the c-axis located at the AF
Brillouin zone boundary, while \Delta(k) is isotropic within the basal plane.
The determined nodal structure is compatible with the resonance peak in the
dynamical susceptibility observed in neutron inelastic scattering experiments.
Based on these results, we conclude that the superconducting pairing function
of UPd_2Al_3 is most likely to be d-wave with a form \Delta(k)=\Delta_0
cos(k_zc)Comment: 10 pages, 9 figure
Thermal Conductivity of the Pyrochlore Superconductor KOs2O6: Strong Electron Correlations and Fully Gapped Superconductivity
To elucidate the nature of the superconducting ground state of the
geometrically frustrated pyrochlore KOs2O6 (Tc=9.6K), the thermal conductivity
was measured down to low temperatures (~Tc/100). We found that the
quasiparticle mean free path is strikingly enhanced below a transition at
Tp=7.5K, indicating enormous electron inelastic scattering in the normal state.
In a magnetic field the conduction at T ->0K is nearly constant up to ~0.4Hc2,
in contrast with the rapid growth expected for superconductors with an
anisotropic gap. This unambiguously indicates a fully gapped superconductivity,
in contrast to the previous studies. These results highlight that KOs2O6 is
unique among superconductors with strong electron correlations.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Let
Effects of Rattling Phonons on the Quasiparticle Excitation and Dynamics in the Superconducting -Pyrochlore KOsO
Microwave penetration depth and surface resistance at 27 GHz are
measured in high quality crystals of KOsO. Firm evidence for
fully-gapped superconductivity is provided from . Below the second
transition at K, the superfluid density shows a step-like
change with a suppression of effective critical temperature .
Concurrently, the extracted quasiparticle scattering time shows a steep
enhancement, indicating a strong coupling between the anomalous rattling motion
of K ions and quasiparticles. The results imply that the rattling phonons help
to enhance superconductivity, and that K sites freeze to an ordered state with
long quasiparticle mean free path below .Comment: 5 pages, 5 figures, to be published in Phys. Rev. Let
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