14,403 research outputs found
Entropy in the Kerr-Newman Black Hole
Entropy of the Kerr-Newman black hole is calculated via the brick wall method
with maintaining careful attention to the contribution of superradiant scalar
modes. It turns out that the nonsuperradinat and superradiant modes
simultaneously contribute to the entropy with the same order in terms of the
brick wall cutoff . In particular, the contribution of the
superradiant modes to the entropy is negative. To avoid divergency in this
method when the angular velocity tends to zero, we propose to intr oduce a
lower bound of angular velocity and to treat the case of the angular momentum
per unit mass separately. Moreover, from the lower bound of the angular
velocity, we obtain the -dependence structure of the brick wall cutoff,
which natu rally requires an angular cutoff . Finally, if the cutoff
values, and , satisfy a proper relation between them, the
resulting entropy satisfies the area law.Comment: 16 pages, Latex, no figures, References are included, Subsection A
and B are reduced to subsection A, Abstract is rewritten, Minor corrections
are include
A note on the factorization method of Niederreiter
AbstractIn this paper, we explicitly obtain the coefficient matrix arising from a linearization of Niederreiter's factorization algorithm and analyze the complexity of setting it up. It turns out that its setup cost is linear both in the degree of a polynomial to be factored and in the size of the base field
Electrical Investigation of the Oblique Hanle Effect in Ferromagnet/Oxide/Semiconductor Contacts
We have investigated the electrical Hanle effect with magnetic fields applied
at an oblique angle ({\theta}) to the spin direction (the oblique Hanle effect,
OHE) in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal
measurement scheme. The electrical oblique Hanle signals obtained in
CoFe/MgO/Si and CoFe/MgO/Ge contacts show clearly different line shapes
depending on the spin lifetime of the host SC. Notably, at moderate magnetic
fields, the asymptotic values of the oblique Hanle signals (in both contacts)
are consistently reduced by a factor of cos^2({\theta}) irrespective of the
bias current and temperature. These results are in good agreement with
predictions of the spin precession and relaxation model for the electrical
oblique Hanle effect. At high magnetic fields where the magnetization of CoFe
is significantly tilted from the film plane to the magnetic field direction, we
find that the observed angular dependence of voltage signals in the CoFe/MgO/Si
and CoFe/MgO/Ge contacts are well explained by the OHE, considering the
misalignment angle between the external magnetic field and the magnetization of
CoFe.Comment: 19 pages, 8 figure
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