Hydrogen patterning of Ga1-xMnxAs for planar spintronics

We demonstrate two patterning techniques based on hydrogen passivation of Ga1-xMnxAs to produce isolated ferromagnetically active regions embedded uniformly in a paramagnetic, insulating host. The first method consists of selective hydrogenation of Ga1-xMnxAs by lithographic masking. Magnetotransport measurements of Hall-bars made in this manner display the characteristic properties of the hole-mediated ferromagnetic phase, which result from good pattern isolation. Arrays of Ga1-xMnxAs dots as small as 250 nm across have been realized by this process. The second process consists of blanket hydrogenation of Ga1-xMnxAs followed by local reactivation using confined low-power pulsed-laser annealing. Conductance imaging reveals local electrical reactivation of micrometer-sized regions that accompanies the restoration of ferromagnetism. The spatial resolution achievable with this method can potentially reach <100 nm by employing near-field laser processing. The high spatial resolution attainable by hydrogenation patterning enables the development of systems with novel functionalities such as lateral spin-injection as well as the exploration of magnetization dynamics in individual and coupled structures made from this novel class of semiconductors.Comment: ICDS-24, July 2007. 8 pages with 4 figure

Magnetic Properties of Enriched 195Pt Metals

金沢大学理工研究域数物科学系An enriched 195Pt system was investigated by magnetic and NMR measurements. Anomalous large magnetic moments are distinctly observed in enriched 195Pt wire samples produced by ORNL and in enriched thin-film samples. In the enriched powder and natural wire samples, weak anomalous large magnetic moments were also observed in magnetic measurements. These anomalous large magnetic moments were discussed by the induced giant magnetic moments of Fe impurity. The induced magnetic moments are different in wire samples and powder samples. © 2009 Springer Science+Business Media, LLC

Status of GRB Observations with the Suzaku Wideband All-sky Monitor

The Wide-band All-sky Monitor (WAM) is a function of the large lateral BGO shield of the Hard X-ray Detector (HXD) onboard Suzaku. Its large geometrical area of 800 cm^2 per side, the large stopping power for the hard X-rays and the wide-field of view make the WAM an ideal detector for gamma-ray bursts (GRBs) observations in the energy range of 50-5000 keV. In fact, the WAM has observed 288 GRBs confirmed by other satellites, till the end of May 2007.Comment: 4 pages, 4 figures, to be published in the proceedings of ''Gamma Ray Bursts 2007'', Santa Fe, New Mexico, November 5-

Interlayer Coherence in the ν=1\nu=1 and ν=2\nu=2 Bilayer Quantum Hall States

We have measured the Hall-plateau width and the activation energy of the bilayer quantum Hall (BLQH) states at the Landau-level filling factor $\nu=1$ and 2 by tilting the sample and simultaneously changing the electron density in each quantum well. The phase transition between the commensurate and incommensurate states are confirmed at $\nu =1$ and discovered at $\nu =2$. In particular, three different $\nu =2$ BLQH states are identified; the compound state, the coherent commensurate state, and the coherent incommensurate state.Comment: 4 pages including 5 figure

Vibrational effect on the fragmentation dynamics of the C K-shell excited CF2CH2

Photoabsorption cross-sections of CF2CH2 were measured in the carbon K-edge region and linear time-of-flight mass spectra were acquired at some photon energies across the two π* peaks. The kinetic energy distributions of CH2+ and CF2+ with two components were deduced from the analysis of the mass spectra. The CH2+ ion with high kinetic energies increases with the extent of vibrational excitation of the CF 1s-1π* state, indicating that molecular vibrations play an important role in the photofragmentation of the inner-shell excited molecule

Synchrotron Radiation Time Gate Quartz Device For Nuclear Resonant Scattering

A synchrotron radiation time gate with X-cut quartz resonator has been constructed for use on nuclear resonant scattering at ultrahigh brilliance beam lines. The purpose is to discriminate the electronic scattered prompt (zero time) from the time delayed nuclear scattered photons. The special feature of this device is the possibility of adjusting the time modulation width of the gate without changing the frequency. © 1995 American Institute of Physics.6622235223