226 research outputs found
Dynamic nuclear polarization induced by hot electrons
A new method for local dynamic nuclear polarization is demonstrated in a
GaAs/AlGaAs heterostructure at the Landau level filling factor . Using a
narrow channel sample, where the width varies stepwise along the electron flow,
we find that electron cooling (heating) causes the polarization of nuclear
spins against (toward) the external magnetic field at liquid helium
temperatures. The longitudinal nuclear spin relaxation rate varies
exponentially with inverse temperature.Comment: 3 pages, 3 figure
Magnetoresistance and spin polarization in the insulating regime of a Si two-dimensional electron system
We have studied the magnetoresistance in a high-mobility Si inversion layer
down to low electron concentrations at which the longitudinal resistivity
has an activated temperature dependence. The angle of the magnetic
field was controlled so as to study the orbital effect proportional to the
perpendicular component for various total strengths . A
dip in , which corresponds to the Landau level filling factor of
, survives even for high resistivity of at
. The linear -dependence of the value of
at the dip for low indicates that a ferromagnetic
instability does not occur even in the far insulating regime.Comment: 6 pages, 7 figures, submitted to PR
Quantum Hall effect at cleaved InSb surfaces and low-temperature annealing effect
We have performed low-temperature in-plane magnetotransport measurements on
two-dimensional electron systems induced by deposition of Ag at {\it in situ}
cleaved surfaces of {\it p}-type InSb. The quantum Hall effect was observed
even at low magnetic fields around 2 T. The surface electron density and the
electron mobility exhibit strong dependence on the Ag-coverage and the
annealing temperature in the range of 15-40 K. The annealing effect suggests
that the surface morphology strongly affects the properties of the
two-dimensional electron systems.Comment: 3 pages, 2 figure
Bonding Behavior between Niobium and Reaction-Sintered SiC(Materials, Metallurgy & Weldability)
Evidence for Two-Dimensional Spin-Glass Ordering in Submonolayer Fe Films on Cleaved InAs Surfaces
Magnetotransport measurements have been performed on two-dimensional electron
gases formed at InAs(110) surfaces covered with a submonolayer of Fe.
Hysteresis in the magnetoresistance, a difference in remanent magnetoresistance
between zero-field-cooling procedures and field-cooling procedures, and
logarithmic time-dependent relaxation after magnetic field sweep are clearly
observed at 1.7 K for a coverage of 0.42 monolayer. These features are
associated with spin-glass ordering in the Fe film.Comment: 4 pages, 3 figure
Development of fully-automated synthesis systems
This paper describes the development of fully-automated synthesis systems for preparing and isolating various kinds of pharmaceutical
compounds. The systems are versatile, and are able to perform
most of the chemical reactions currently used in organic chemistry,
with the exception of hydrogenation which requires high pressure.
An additional benefit is the very user-friendly software
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