64,700 research outputs found

### Room Temperature Reversible Spin Hall Effect

Reversible spin Hall effect comprising the "direct" and "inverse" spin Hall
effects was successfully detected at room temperature. This experimental
demonstration proves the fundamental relations called Onsager reciprocal
relations between spin and charge currents. A platinum wire with a strong
spin-orbit interaction is used not only as a spin current absorber but also as
a spin current source in the present lateral structure specially designed for
clear detection of both charge and spin accumulations via the spin-orbit
interaction. The obtained spin Hall conductivity is much larger than the
reported value of Aluminum wire because of the larger spin-orbit interaction.Comment: 12 pages, 4 figure

### Nonlocal spin Hall effect and spin-orbit interaction in nonmagnetic metals

Spin Hall effect in a nonlocal spin-injection device is theoretically
studied. Using a nonlocal spin-injection technique, a pure spin current is
created in a nonmagnetic metal (N). The spin current flowing in N is deflected
by spin-orbit scattering to induce the Hall current in the transverse direction
and accumulate charge at the edges of N, yielding the spin-current induced Hall
effect. We propose a method for extracting information for spin-orbit
scattering in nonmagnetic metals.Comment: 2 pages, 1 figures; accepted in JMMM (Proceedings of ICM2006, Kyoto

### Gauge Fixing and Scattering Amplitudes in String Field Theory Expanded around Universal Solutions

We study a gauge fixed action of open string field theory expanded around the
universal solution which has been found as an analytic classical solution with
one parameter a. For a>-1/2, we are able to reproduce open string scattering
amplitudes in the theory fixed in the Siegel gauge. At a=-1/2, all scattering
amplitudes vanish and there is no open string excitation in the gauge fixed
theory. These results support the conjecture that the universal solution can be
regarded as pure gauge or the tachyon vacuum solution.Comment: 23 pages, LaTeX with PTPTeX.cls, 1 eps figure. minor corrections,
published versio

### Thermodynamical Bethe Ansatz and Condensed Matter

The basics of the thermodynamic Bethe ansatz equation are given. The simplest
case is repulsive delta function bosons, the thermodynamic equation contains
only one unknown function. We also treat the XXX model with spin 1/2 and the
XXZ model and the XYZ model. This method is very useful for the investigation
of the low temperature thermodynamics of solvable systems.Comment: 52 pages, 6 figures, latex, lamuphys.st

### Three Dimensional Heisenberg Spin Glass Models with and without Random Anisotropy

We reexamine the spin glass (SG) phase transition of the $\pm J$ Heisenberg
models with and without the random anisotropy $D$ in three dimensions ($d = 3$)
using complementary two methods, i.e., (i) the defect energy method and (ii)
the Monte Carlo method. We reveal that the conventional defect energy method is
not convincing and propose a new method which considers the stiffness of the
lattice itself. Using the method, we show that the stiffness exponent $\theta$
has a positive value ($\theta > 0$) even when $D = 0$. Considering the
stiffness at finite temperatures, we obtain the SG phase transition temperature
of $T_{\rm SG} \sim 0.19J$ for $D = 0$. On the other hand, a large scale MC
simulation shows that, in contrary to the previous results, a scaling plot of
the SG susceptibility $\chi_{\rm SG}$ for $D = 0$ is obtained using almost the
same transiton temperature of $T_{\rm SG} \sim 0.18J$. Hence we believe that
the SG phase transition occurs in the Heisenberg SG model in $d = 3$.Comment: 15 pages, 9 figures, to be published in J. Phys.

### Cold r-Process in Neutrino-Driven Winds

The r-process in a low temperature environment is explored, in which the
neutron emission by photodisintegration does not play a role (cold r-process).
A semi-analytic neutrino-driven wind model is utilized for this purpose. The
temperature in a supersonically expanding outflow can quickly drop to a few
10^8 K, where the (n, gamma)-(gamma, n) equilibrium is never achieved during
the heavy r-nuclei synthesis. In addition, the neutron capture competes with
the beta-decay owing to the low matter density. Despite such non-standard
physical conditions for the cold r-process, a solar-like r-process abundance
curve can be reproduced. The cold r-process predicts, however, the low lead
production compared to that expected in the traditional r-process conditions,
which can be a possible explanation for the low lead abundances found in a
couple of r-process-rich Galactic halo stars.Comment: 5 pages, 3 figures, accepted for publication in ApJ

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