905 research outputs found
Domain-wall resistance in ferromagnetic (Ga,Mn)As
A series of microstructures designed to pin domain-walls (DWs) in (Ga,Mn)As
with perpendicular magnetic anisotropy has been employed to determine extrinsic
and intrinsic contributions to DW resistance. The former is explained
quantitatively as resulting from a polarity change in the Hall electric field
at DW. The latter is one order of magnitude greater than a term brought about
by anisotropic magnetoresistance and is shown to be consistent with
disorder-induced misstracing of the carrier spins subject to spatially varying
magnetization
More on the Isomorphism
In this paper we revisit the isomorphism to
apply to some subjects in Quantum Computation and Mathematical Physics.
The unitary matrix by Makhlin giving the isomorphism as an adjoint action
is studied and generalized from a different point of view. Some problems are
also presented.
In particular, the homogeneous manifold which characterizes
entanglements in the case of is studied, and a clear-cut calculation of
the universal Yang-Mills action in (hep-th/0602204) is given for the abelian
case.Comment: Latex ; 19 pages ; 5 figures ; minor changes. To appear in
International Journal of Geometric Methods in Modern Physics (vol.4, no.3
On the Magic Matrix by Makhlin and the B-C-H Formula in SO(4)
A closed expression to the Baker-Campbell-Hausdorff (B-C-H) formula in SO(4)
is given by making use of the magic matrix by Makhlin. As far as we know this
is the {\bf first nontrivial example} on (semi-) simple Lie groups summing up
all terms in the B-C-H expansion.Comment: Latex ; 11 pages ; 1 figure ; minor changes. To appear in
International Journal of Geometric Methods in Modern Physics (vol.4, no.5 or
6), 200
Design and Observation of Steep Reinforced Embankments
Using the design method proposed by R. A. Jewell et al. numerous steep reinforced embankments have been constructed in the authors’ home country since the year 1984. In fact these soil structures are built with the reinforcement of polymer grids (the so-called geogrids invented by F. B. Mercer of U.K.) which have a unique structural composition with high-tensile and low-ductility characteristics. This paper deals with first the development of steep reinforced soil structures and their design method, and then introduces a well-documented case history of steep reinforced embankment. The authors propose a current design method developed on the basis of the findings obtained from the observations at several steep reinforced embankments including the present one of the case history. And finally an ultimate seismic-design method for steep reinforced embankment adopted recently in Japan is presented
Velocity of domain-wall motion induced by electrical current in a ferromagnetic semiconductor (Ga,Mn)As
Current-induced domain-wall motion with velocity spanning over five orders of
magnitude up to 22 m/s has been observed by magneto-optical Kerr effect in
(Ga,Mn)As with perpendicular magnetic anisotropy. The data are employed to
verify theories of spin-transfer by the Slonczewski-like mechanism as well as
by the torque resulting from spin-flip transitions in the domain-wall region.
Evidence for domain-wall creep at low currents is found.Comment: 5 pages, 3 figure
Seismic Response and Liquefaction Analysis by an Approximate Method
Presented is a simplified procedure for performing the dynamic effective stress analysis. An equivalent linear method is applied to the procedure. It is assumed, in this method, that the variations of the shear modulus and damping factor due to strain level and effective stress are independent one another. That is, firstly the total stress analysis is done in order to obtain the effective strain. Then the effective stress analysis is carried out and the moduli are varied due to the variation of the effective stress only. The accuracy of the result is checked by comparing it with that of nonlinear solution
Thermal Effects in the dynamics of disordered elastic systems
Many seemingly different macroscopic systems (magnets, ferroelectrics, CDW,
vortices,..) can be described as generic disordered elastic systems.
Understanding their static and dynamics thus poses challenging problems both
from the point of view of fundamental physics and of practical applications.
Despite important progress many questions remain open. In particular the
temperature has drastic effects on the way these systems respond to an external
force. We address here the important question of the thermal effect close to
depinning, and whether these effects can be understood in the analogy with
standard critical phenomena, analogy so useful to understand the zero
temperature case. We show that close to the depinning force temperature leads
to a rounding of the depinning transition and compute the corresponding
exponent. In addition, using a novel algorithm it is possible to study
precisely the behavior close to depinning, and to show that the commonly
accepted analogy of the depinning with a critical phenomenon does not fully
hold, since no divergent lengthscale exists in the steady state properties of
the line below the depinning threshold.Comment: Proceedings of the International Workshop on Electronic Crystals,
Cargese(2008
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