3,708 research outputs found
Analogs of Rashba-Edelstein effect from density functional theory
Studies of structure-property relationships in spintronics are essential for
the design of materials that can fill specific roles in devices. For example,
materials with low symmetry allow unconventional configurations of
charge-to-spin conversion which can be used to generate efficient spin-orbit
torques. Here, we explore the relationship between crystal symmetry and
geometry of the Rashba-Edelstein effect (REE) that causes spin accumulation in
response to an applied electric current. Based on a symmetry analysis performed
for 230 crystallographic space groups, we identify classes of materials that
can host conventional or collinear REE. Although transverse spin accumulation
is commonly associated with the so-called 'Rashba materials', we show that the
presence of specific spin texture does not easily translate to the
configuration of REE. More specifically, bulk crystals may simultaneously host
different types of spin-orbit fields, depending on the crystallographic point
group and the symmetry of the specific -vector, which, averaged over the
Brillouin zone, determine the direction and magnitude of the induced spin
accumulation. To explore the connection between crystal symmetry, spin texture,
and the magnitude of REE, we perform first-principles calculations for
representative materials with different symmetries. We believe that our results
will be helpful for further computational and experimental studies, as well as
the design of spintronics devices.Comment: 10 pages, 5 figure
Spectral Correlation in Incommensurate Multi-Walled Carbon Nanotubes
We investigate the energy spectra of clean incommensurate double-walled
carbon nanotubes, and find that the overall spectral properties are described
by the so-called critical statistics of Anderson metal-insulator transition. In
the energy spectra, there exist three different regimes characterized by
Wigner-Dyson, Poisson, and semi-Poisson distributions. This feature implies
that the electron transport in incommensurate multi-walled nanotubes can be
either diffusive, ballistic, or intermediate between them, depending on the
position of the Fermi energy.Comment: final version to appear in Phys. Rev. Let
Search for the Electric Dipole Moment of the tau Lepton
We have searched for a CP violation signature arising from an electric dipole
moment (d_tau) of the tau lepton in the e+e- -> tau+tau- reaction. Using an
optimal observable method and 29.5 fb^{-1} of data collected with the Belle
detector at the KEKB collider at sqrt{s} = 10.58 GeV, we find Re(d_tau) = (1.15
+- 1.70) x 10^{-17} ecm and Im(d_tau) = (-0.83 +- 0.86) x 10^{-17} ecm and set
the 95% confidence level limits -2.2 < Re(d_tau) < 4.5 (10^{-17}ecm) and -2.5 <
Im(d_tau) < 0.8 (10^{-17}ecm).Comment: 15 pages, LaTeX, 21 figures, submitted to Phys. Lett.
Dust in the bright supernova remnant N49 in the LMC
We investigate the dust associated with the supernova remnant (SNR) N49 in
the Large Magellanic Cloud (LMC) as observed with the Herschel Space
Observatory. N49 is unusually bright because of an interaction with a molecular
cloud along its eastern edge. We have used PACS and SPIRE to measure the far IR
flux densities of the entire SNR and of a bright region on the eastern edge of
the SNR where the SNR shock is encountering the molecular cloud. Using these
fluxes supplemented with archival data at shorter wavelengths, we estimate the
dust mass associated with N49 to be about 10 Msun. The bulk of the dust in our
simple two-component model has a temperature of 20-30 K, similar to that of
nearby molecular clouds. Unfortunately, as a result of the limited angular
resolution of Herschel at the wavelengths sampled with SPIRE, the uncertainties
are fairly large. Assuming this estimate of the dust mass associated with the
SNR is approximately correct, it is probable that most of the dust in the SNR
arises from regions where the shock speed is too low to produce significant
X-ray emission. The total amount of warm 50-60 K dust is ~0.1 or 0.4 Msun,
depending on whether the dust is modeled in terms of carbonaceous or silicate
grains. This provides a firm lower limit to the amount of shock heated dust in
N49.Comment: accepted by the Astronomy & Astrophysics Lette
Search for neutrinoless decays tau -> 3l
We have searched for neutrinoless tau lepton decays into three charged
leptons using an 87.1 fb^{-1} data sample collected with the Belle detector at
the KEKB e^+e^- collider. Since the number of signal candidate events is
compatible with that expected from the background, we set 90% confidence level
upper limits on the branching fractions in the range (1.9-3.5) x 10^{-7} for
various decay modes tau -> l l l where l represents e or mu.Comment: 12 pages, 4figure
Evidence of B0 --> rho0 pi0
We present the first evidence of the decay B0 --> rho0 pi0, using 140fb^-1 of
data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB
asymmetric e+e- collider. We detect a signal with a significance of 3.5
standard deviations, and measure the branching fraction to be Br(B0 ->- rho0
pi0) = (5.1 +/- 1.6(stat) +/- 0.9(syst))*10^-6.Comment: RevTex4, 5 pages, 4 figures, submitted to Phys.Rev.Let
Measurement of Branching Fractions for Decays
We report measurements of branching fractions for charged and neutral decays where the meson is reconstructed in the and decay
channels. The neutral channel is a CP eigenstate and can be used to
measure the CP violation parameter . We also report the first
observation of the mode. The results are based on an
analysis of 29.1 fb of data collected by the Belle detector at KEKB.Comment: To appear in Physical Review Letter
Observation of the decay B^0->D+D*-
We report the first observation of the decay B^0->D+-D*-+ with the Belle
detector at the KEKB e^+e^- collider operated at the Upsilon(4S) resonance. The
sum of branching fractions B(B^0->D+D*-)+B(B^0->D-D*+) is measured to be
(1.17+-0.26+0.22-0.25)x10^-3 using the full reconstruction method where both
charmed mesons from B^0 decays are reconstructed. A consistent value
((1.48+-0.38+0.28-0.31)x10^-3) is obtained using a partial reconstruction
technique that only uses the slow pion from the D*- ->bar D^0pi- decay and a
fully reconstructed D+ to reconstruct the B^0.Comment: 10 pages, 3 figure
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