1,400 research outputs found
Real-space observation of current-driven domain wall motion in submicron magnetic wires
Spintronic devices, whose operation is based on the motion of a magnetic
domain wall (DW), have been proposed recently. If a DW could be driven directly
by flowing an electric current instead of a magnetic field, the performance and
functions of such device would be drastically improved. Here we report
real-space observation of the current-driven DW motion by using a well-defined
single DW in a micro-fabricated magnetic wire with submicron width. Magnetic
force microscopy (MFM) visualizes that a single DW introduced in the wire is
displaced back and forth by positive and negative pulsed-current, respectively.
We can control the DW position in the wire by tuning the intensity, the
duration and the polarity of the pulsed-current. It is, thus, demonstrated that
spintronic device operation by the current-driven DW motion is possible.Comment: Accepted and published in PR
Novel theoretical approach in photoemission spectroscopy: application to isotope effect and boron-doped diamond
A new path-integral theory is developed to calculate the photoemission
spectra (PES) of correlated many-electron systems. The application to the study
on Bi2Sr2CaCu2O8 (Bi2212) and boron-doped diamond (BDD) is discussed in
details. It is found that the isotopic shift in the angle-resolved
photoemission spectra of Bi2212 is due to the off-diagonal quadratic
electron-phonon (e-ph) coupling, whereas the presence of electron-electron
repulsion partially suppresses this effect. For the BDD, a semiconductor-metal
phase transition, which is induced by increasing the e-ph coupling and dopant
concentration, is reproduced by our theory. Additionally, the presence of Fermi
edge and phonon step-like structure in PES is found to be due to a co-existence
of itinerant and localized electronic states in BDD.Comment: 6 pages, 4 figures, Procs. of LEHTSC 2007, submitted to J. Phys.:
Conf. Se
Propagation of a magnetic domain wall in magnetic wires with asymmetric notches
The propagation of a magnetic domain wall (DW) in a submicron magnetic wire
consisting of a magnetic/nonmagnetic/magnetic trilayered structure with
asymmetric notches was investigated by utilizing the giant magnetoresistance
effect. The propagation direction of a DW was controlled by a pulsed local
magnetic field, which nucleates the DW at one of the two ends of the wire. It
was found that the depinning field of the DW from the notch depends on the
propagation direction of the DW.Comment: 12 pages, 3 figure
Photogenerated Carriers in SrTiO3 Probed by Mid-Infrared Absorption
Infrared absorption spectra of SrTiO have been measured under
above-band-gap photoexcitations to study the properties of photogenerated
carriers, which should play important roles in previously reported photoinduced
phenomena in SrTiO. A broad absorption band appears over the entire
mid-infrared region under photoexcitation. Detailed energy, temperature, and
excitation power dependences of the photoinduced absorption are reported. This
photo-induced absorption is attributed to the intragap excitations of the
photogenerated carriers. The data show the existence of a high density of
in-gap states for the photocarriers, which extends over a wide energy range
starting from the conduction and valence band edges.Comment: 5 pages, 5 figures, submitted to J. Phys. Soc. Jp
Filamentous phage associated with recent pandemic strains of Vibrio parahaemolyticus.
A group of pandemic strains of Vibrio parahaemolyticus has recently appeared in Asia and North America. We demonstrate that a filamentous phage is specifically associated with the pandemic V. parahaemolyticus strains. An open reading frame unique to the phage is a useful genetic marker to identify these strains
Analysis of Downhole Logs, Leg 57, Deep Sea Drilling Project
All sites drilled on Leg 57 were logged as weather
conditions permitted. The logging was done by the Singapore
office of Schlumberger, and because of short
notice the special logging tools required to pass through
the Challenger drill pipe were not available. The standard
centralizer, excentralizer, and caliper tools were
not appropriate, and those modified aboard ship were
not completely satisfactory. In addition, we suspected
that vertical motion from the ship's heave degraded the
quality of logs. Both the sonic and neutron density tools
were operated beyond their normal working ranges. Despite
these operational difficulties, the logs from different
runs in a hole, both repeat sections and runs with
different tools, show generally the same features. Over
intervals of 5 to 10 meters the field logs seem to be good
indicators of the physical character of the section penetrated
(Carson and Bruns, this volume).
The recovery of continuous core as well as logs differs
from normal industrial drilling practice, in which a
major purpose of logging is to establish lithology. Since
lithology is best established by direct examination, the
log analysis focused less on identifying a specific lithology
than on continuous measurement of in situ
physical properties, especially at Sites 438, 439, and 440,
where recovery was good. However, the logs were used
to establish the lithology of missing intervals, especially
at Site 441, where recovery was poor. Lithology and
physical properties aspects of the log analysis are covered
in the individual site chapters and in a comparative
analysis of laboratory measurements of physical properties
and logged physical parameters (Carson and Bruns,
this volume). In the present chapter we concentrate on
log precision, correlation of key horizons in seismic
records and core lithology, and on fracturing as indicated
by the logs. We do this by using the results of a
study of corrected logs and the derivative products from
computer programs developed by the Scientific Software
Corporation (SSC) and Technology Research Center
and of corrected logs from Schlumberger (available
from DSDP)
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