4,414 research outputs found
High mobility two-dimensional electron system on hydrogen-passivated silicon(111) surfaces
We have fabricated and characterized a field-effect transistor in which an
electric field is applied through an encapsulated vacuum cavity and induces a
two-dimensional electron system on a hydrogen-passivated Si(111) surface. This
vacuum cavity preserves the ambient sensitive surface and is created via room
temperature contact bonding of two Si substrates. Hall measurements are made on
the H-Si(111) surface prepared in aqueous ammonium fluoride solution. We obtain
electron densities up to cm and peak mobilities of
cm/V s at 4.2 K.Comment: to appear in Applied Physics Letter
Integer quantum Hall effect on a six valley hydrogen-passivated silicon (111) surface
We report magneto-transport studies of a two-dimensional electron system
formed in an inversion layer at the interface between a hydrogen-passivated
Si(111) surface and vacuum. Measurements in the integer quantum Hall regime
demonstrate the expected sixfold valley degeneracy for these surfaces is
broken, resulting in an unequal occupation of the six valleys and anisotropy in
the resistance. We hypothesize the misorientation of Si surface breaks the
valley states into three unequally spaced pairs, but the observation of odd
filling factors, is difficult to reconcile with non-interacting electron
theory.Comment: 4 pages, 4 figures, to appear in Physical Review Letter
Modeling of micro- and nano-scale domain recording by high-voltage atomic force microscopy in ferroelectrics-semiconductors
The equilibrium sizes of micro- and nano-domains caused by electric field of
atomic force microscope tip in ferroelectric semiconductor crystals have been
calculated. The domain was considered as a prolate semi-ellipsoid with rather
thin domain walls. For the first time we modified the Landauer model allowing
for semiconductor properties of the sample and the surface energy of the domain
butt. The free carriers inside the crystal lead to the formation of the
screening layer around the domain, which partially shields its interior from
the depolarization field. We expressed the radius and length of the domain
though the crystal material parameters (screening radius, spontaneous
polarization value, dielectric permittivity tensor) and atomic force microscope
tip characteristics (charge, radius of curvature). The obtained dependence of
domain radius via applied voltage is in a good quantitative agreement with the
ones of submicron ferroelectric domains recorded by high-voltage atomic force
and scanning probe microscopy in LiNbO3 and LiTaO3 crystals.Comment: 21 pages, 5 figure
Implementation of the Explicit Group Iterative Method for Solving Image Blurring Problem using Non-Linear Diffusion Equations
Diffusion equations have been known to solve various image processing problems. This study employs the diffusion equations as the partial difference equations (PDEs)-based image processing techniques for image blurring which also can be refer as the process of image smoothing. The solutions of diffusion equations were obtained using the iterative algorithms and thereafter applied in the image blurring processes. The images were blurred without destroying the crucial information of an image that need to be preserve such as sharp edges, lines and shapes as the diffusion occurs inside the image locations, where the images with different sizes were tested. In terms of performance comparison, the standard point Gauss-Seidel and two-point Explicit Group (2-EG) methods were considered to produce the same quality image of classical point iterative method which is Jacobi. The numerical results showed that 2-EG iterative method capable to smooth the inner region of the images faster compared to the standard point iterative method. It was shown that the 2-EG iterative method more efficient in reducing the number of iterations and computational time than the standard point iterative method
Sistem Informasi Pengelolaan Nilai SMPN 2 Mojolaban
Sistem Informasi Pengelolaan Nilai SMPN 2 Mojolaban merupakan sistem yang dibangun dengan tujuan untuk memudahkan pihak sekolah dalam proses pendataan siswa, pengolahan nilai siswa dan untuk memudahkan orang tua siswa
untuk memantau hasil kegiatan belajar anaknya selama disekolah, sehingga para orang tua memperoleh informasi nilai siswa dengan lebih cepat dan efisien.
Metode perancangan sistem yang digunakan adalah adalah SDLC (System Development Life Cycle) yaitu proses yang digunakan oleh analisis sistem untuk mengembangkan sistem informasi mulai dari analisis/penentuan kebutuhan, perancangan sistem, implementasi sistem, perawatan sistem dan kebijakan
perencanaan sistem/penyerahan kepada konsumen.
Dengan tahapan yang telah dibuat, Sistem Informasi Pengelolaan Nilai SMPN 2 Mojolaban berhasil diwujudkan. Serta system Informasi dapat berjalan sebagaimana mestinya yang diinginkan dan sesuai dengan tujuan system Informasi dibuat. Para guru lebih mudah mengelola nilai siswa dan tidak membutuhkan waktu yang lama sehingga siswa lebih cepat mengetahui informasi nilai mereka
Study of Magnetic Properties of A_2B^'NbO_6 (A=Ba,Sr, (BaSr): and B^'=Fe and Mn) double perovskites
We have studied the magnetic properties of Ba_2FeNbO_6 and Ba_2MnNbO_6. it is
seen that Ba_2FeNbO_6 is an antiferromagnet with a weak ferromagnetic behaviour
at 5K while Ba_2MnNbO_6 shows two magnetic transitions one at 45 K and the
other at 12K. Electron spin resonance (ESR) measurements at room temperature
show that the Mn compound does not show any Jahn-Teller distortion. It is also
seen that the Neel temperature of the A_2FeNbO_6 (A=Ba,Sr, BaSr) compounds do
not vary significantly. However variations in the average A-site ionic radius
influence the formation of short range correlations that persist above T_N.Comment: 10 oages, 5 figures, MMM, to appear in J.Appl.Phy
OPTIMIZATION OF FLYING ROBOTS GROUP BASED ON UNMANNED AERIAL VEHICLES
LYSENKO, Dr. Sc., Senior lecturer Eng. Нelen TACHININA, PhD, N.A. TYMOSHENKO, post-graduate student National Aviation University, Ukraine REZUMAT. Este propusă o metodologie de conversie a sistemului compus dinamic într-un sistem discontinuu cu dimensiunea vectorilor de stare şi control care se schimbă în momentele de schimbare structurală. Cuvinte cheie: sistem dynamic, optimizare, traiectorie. ABSTRACT. The method of converting the compound dynamic system to the branching system with transient size of state and control vectors at a moment of structural changes is proposed
Temperature-dependent transport in a sixfold degenerate two-dimensional electron system on a H-Si(111) surface
Low-field magnetotransport measurements on a high mobility (mu=110,000
cm^2/Vs) two-dimensional (2D) electron system on a H-terminated Si(111) surface
reveal a sixfold valley degeneracy with a valley splitting <= 0.1 K. The
zero-field resistivity rho_{xx} displays strong temperature dependence for 0.07
< T < 25 K as predicted for a system with high degeneracy and large mass. We
present a method for using the low-field Hall coefficient to probe intervalley
momentum transfer (valley drag). The relaxation rate is consistent with Fermi
liquid theory, but a small residual drag as T->0 remains unexplained.Comment: 5 pages, 4 figures; revised and slightly shortened for publication
Out of equilibrium electronic transport properties of a misfit cobaltite thin film
We report on transport measurements in a thin film of the 2D misfit Cobaltite
. Dc magnetoresistance measurements obey the modified
variable range hopping law expected for a soft Coulomb gap. When the sample is
cooled down, we observe large telegraphic-like fluctuations. At low
temperature, these slow fluctuations have non Gaussian statistics, and are
stable under a large magnetic field. These results suggest that the low
temperature state is a glassy electronic state. Resistance relaxation and
memory effects of pure magnetic origin are also observed, but without aging
phenomena. This indicates that these magnetic effects are not glassy-like and
are not directly coupled to the electronic part.Comment: accepted in Phys Rev B, Brief report
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