240 research outputs found
The Ebers-Moll model for magnetic bipolar transistors
The equivalent electrical circuit of the Ebers-Moll type is introduced for
magnetic bipolar transistors. In addition to conventional diodes and current
sources, the new circuit comprises two novel elements due to spin-charge
coupling. A classification scheme of the operating modes of magnetic bipolar
transistors in the low bias regime is presented.Comment: 4 pages, 2 figure
Spin Accumulation in the Extrinsic Spin Hall Effect
The drift-diffusion formalism for spin-polarized carrier transport in
semiconductors is generalized to include spin-orbit coupling. The theory is
applied to treat the extrinsic spin Hall effect using realistic boundary
conditions. It is shown that carrier and spin diffusion lengths are modified by
the presence of spin-orbit coupling and that spin accumulation due to the
extrinsic spin Hall effect is strongly and qualitatively influenced by boundary
conditions. Analytical formulas for the spin-dependent carrier recombination
rates and inhomogeneous spin densities and currents are presented.Comment: 5 pages, 3 figure
Current distribution inside Py/Cu lateral spin-valve device
We have investigated experimentally the non-local voltage signal (NLVS) in
the lateral permalloy (Py)/Cu/Py spin valve devices with different width of Cu
stripes. We found that NLVS strongly depends on the distribution of the
spin-polarized current inside Cu strip in the vicinity of the Py-detector. To
explain these data we have developed a diffusion model describing spatial (3D)
distribution of the spin-polarized current in the device. The results of our
calculations show that NLVS is decreased by factor of 10 due to spin
flip-scattering occurring at Py/Cu interface. The interface resistivity on
Py/Cu interface is also present, but its contribution to reduction of NLVS is
minor. We also found that most of the spin-polarized current is injected within
the region 30 nm from Py-injector/Cu interface. In the area at Py-detector/Cu
interface, the spin-polarized current is found to flow mainly close on the
injector side, with 1/e exponential decay in the magnitude within the distance
80 nm.Comment: 10 pages, 14 figure
A case report: isolation of alysiella filiformis from pig"s lungs
Alysiella filiformis is considered a common resident in the oral cavities of many animals. All reports of Alysiella indicate that it is restricted to the oral cavity of warm-blooded vertebrates, where it apparently is nonpathogenic. However, increased losses of young pigs occured in one farm in Serbia. Spumous content in bronchia and partly clotted blood in blood vesels o f the lungs were present. Characteristic signs of oedema disease were present and E. coli serogroup 0139 was isolated. Furthermore, Alysiella filiformis was the single agent isolated from the lungs of diseased pigs. This is the first isolation of Alysiella filiformis from pig lungs
Reconfigurable nanoelectronics using graphene based spintronic logic gates
This paper presents a novel design concept for spintronic nanoelectronics
that emphasizes a seamless integration of spin-based memory and logic circuits.
The building blocks are magneto-logic gates based on a hybrid
graphene/ferromagnet material system. We use network search engines as a
technology demonstration vehicle and present a spin-based circuit design with
smaller area, faster speed, and lower energy consumption than the
state-of-the-art CMOS counterparts. This design can also be applied in
applications such as data compression, coding and image recognition. In the
proposed scheme, over 100 spin-based logic operations are carried out before
any need for a spin-charge conversion. Consequently, supporting CMOS
electronics requires little power consumption. The spintronic-CMOS integrated
system can be implemented on a single 3-D chip. These nonvolatile logic
circuits hold potential for a paradigm shift in computing applications.Comment: 14 pages (single column), 6 figure
Angular Dependence of the Nonlinear Transverse Magnetic Moment of YBCO in the Meissner state
The angular dependence of the nonlinear transverse magnetic moment of
untwinned high-quality single crystals of optimally doped YBCO have been
studied at a temperature of 2.5K using a low frequency AC technique. The
absence of any signature at angular period 2\pi/4is analyzed in light of the
numerical predictions of such a signal for a pure d-wave order parameter with
line nodes. Implications of this null result for the existence of a non-zero
gap at all angles on the Fermi surface are discussed.Comment: 4 pages, 2 ps figures (submitted to Phys. Rev. Lett.
Electronic States of Magnetic Quantum Dots
We study quantum states of electrons in magnetically doped quantum dots as a
function of exchange coupling between electron and impurity spins, the strength
of Coulomb interaction, confining potential, and the number of electrons. The
magnetic phase diagram of quantum dots, doped with a large number of magnetic
Mn impurities, can be described by the energy gap in the spectrum of electrons
and the mean field electron-Mn exchange coupling. A competition between these
two parameters leads to a transition between spin-unpolarized and
spin-polarized states, in the absence of applied magnetic field. Tuning the
energy gap by electrostatic control of nonparabolicity of the confining
potential can enable control of magnetization even at the fixed number of
electrons. We illustrate our findings by directly comparing Mn-doped quantum
dots with parabolic and Gaussian confining potential.Comment: 5 pages, 5 figures, Part of Focus on Spintronics in Reduced
Dimension
Charge current in ferromagnet-superconductor junction with pairing state of broken time-reversal symmetry
We calculate the tunneling conductance spectra of a ferromagnetic
metal/insulator/superconductor using the Blonder-Tinkham-Klapwijk (BTK)
formulation. Two possible states for the superconductor are considered with the
time reversal symmetry () broken, i.e., , or
. In both cases the tunneling conductance within the gap
is suppressed with the increase of the exchange interaction due to the
suppression of the Andreev reflection. In the -wave case the
peaks that exist when the ferromagnet is a normal metal in the amplitude of the
s-wave component due to the bound state formation are reduced symmetrically,
with the increase of the exchange field, while in the
-wave case the residual density of states within the gap
develops a dip around E=0 with the increase of the exchange field. These
results would be useful to discriminate between -broken pairing states
near the surface in high- superconductorsComment: 17 pages with 11 figure
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