1,526 research outputs found
National input-output table of Brazil
This paper reports on the basic information about the Brazilian input-output tables. First part presents the history of constructing I-O tables in Brazil, starting from the non-official table of 1959. The second part illustrates some basic features of the last table with the reference year of 2005. It also articulates the issues concerning the integration of the table into 2005 BRICS International Input-Output Table.Brazil; Input-Output; Tables
Quasi-classical path integral approach to supersymmetric quantum mechanics
{}From Feynman's path integral, we derive quasi-classical quantization rules
in supersymmetric quantum mechanics (SUSY-QM). First, we derive a SUSY
counterpart of Gutzwiller's formula, from which we obtain the quantization rule
of Comtet, Bandrauk and Campbell when SUSY is good. When SUSY is broken, we
arrive at a new quantization formula, which is found as good as and even
sometime better than the WKB formula in evaluating energy spectra for certain
one-dimensional bound state problems. The wave functions in the stationary
phase approximation are also derived for SUSY and broken SUSY cases. Insofar as
a broken SUSY case is concerned, there are strong indications that the new
quasi-classical approximation formula always overestimates the energy
eigenvalues while WKB always underestimates.Comment: 13 pages + 5 figures, complete paper submitted as postscript file, to
appear in Phys. Rev.
Manipulation of single electron spin in a GaAs quantum dot through the application of geometric phases: The Feynman disentangling technique
The spin of a single electron in an electrically defined quantum dot in a
2DEG can be manipulated by moving the quantum dot adiabatically in a closed
loop in the 2D plane under the influence of applied gate potentials. In this
paper we present analytical expressions and numerical simulations for the
spin-flip probabilities during the adiabatic evolution in the presence of the
Rashba and Dresselhaus linear spin-orbit interactions. We use the Feynman
disentanglement technique to determine the non-Abelian Berry phase and we find
exact analytical expressions for three special cases: (i) the pure Rashba
spin-orbit coupling, (ii) the pure Dresselhause linear spin-orbit coupling, and
(iii) the mixture of the Rashba and Dresselhaus spin-orbit couplings with equal
strength. For a mixture of the Rashba and Dresselhaus spin-orbit couplings with
unequal strengths, we obtain simulation results by solving numerically the
Riccati equation originating from the disentangling procedure. We find that the
spin-flip probability in the presence of the mixed spin-orbit couplings is
generally larger than those for the pure Rashba case and for the pure
Dresselhaus case, and that the complete spin-flip takes place only when the
Rashba and Dresselhaus spin-orbit couplings are mixed symmetrically.Comment: 11 pages, 6 figure
Magnetism and superconductivity in TaSC (M = Fe, Co, Ni, and Cu)
Magnetic properties of TaSC ( = Fe, Co, Ni, Cu) have
been studied using SQUID DC and AC magnetic susceptibility. In these systems
magnetic ions are intercalated into van der Waals gaps between
adjacent S layers of host superconductor TaSC.
FeTaSC is a quasi 2D -like antiferromagnet on the
triangular lattice. It undergoes an antiferromagnetic phase transition at
(= 117 K). The irreversible effect of magnetization occurs below
, reflecting the frustrated nature of the system. The AF phase coexists
with two superconducting phases with the transition temperatures
K and K. CoTaSC is a quasi 2D Ising-like
antiferromagnet on the triangular lattice. The antiferromagnetic phase below
K coexists with a superconducting phase below K.
Both NiTaSC and CuTaSC are
superconductors with ( K for Ni and 6.4 K for Cu) and
(= 4.6 K common to TaSC). Very small effective magnetic
moments suggest that Ni and Cu spins are partially delocalized.Comment: 15 pages, 17 figures, and 3 table
An Effective Reduction of Critical Current for Current-Induced Magnetization Switching by a Ru Layer Insertion in an Exchange-Biased Spin-Valve
Recently it has been predicted that a spin-polarized electrical current
perpendicular-to-plane (CPP) directly flowing through a magnetic element can
induce magnetization switching through spin-momentum transfer. In this letter,
the first observation of current-induced magnetization switching (CIMS) in
exchange-biased spin-valves (ESPVs) at room temperature is reported. The ESPVs
show the CIMS behavior under a sweeping dc current with a very high critical
current density. It is demonstrated that a thin Ruthenium (Ru) layer inserted
between a free layer and a top electrode effectively reduces the critical
current densities for the CIMS. An "inverse" CIMS behavior is also observed
when the thickness of the free layer increases.Comment: 15 pages with figure
Possible observation of energy level quantization in an intrinsic Josephson junction
Energy level quantization (ELQ) is studied to clarify the macroscopic quantum
dynamics of the d-wave Josephson junction (JJ). The influences of the nodal
quasiparticles of d-wave superconductivity on the damping effect are
numerically evaluated on the basis of a phenomenological model. The
calculation, based on realistic parameters for a Bi2Sr2CaCu2O8+d (Bi2212)
intrinsic JJ, shows that the observation of ELQ is possible when the sweep rate
of the bias current exceeds 10 A/sec. High-sweep- rate measurements (121A/sec)
performed on a Bi2212 intrinsic JJ result in the appearance of multiple peaks
in the switching current distribution suggesting the realization of ELQ in the
d-wave JJ.Comment: 5 pages, 3 figure
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