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$_3$ 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$_3$. 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)