62 research outputs found
Novel Charge Ordering in the Trimer Iridium Oxide BaIrO3
We have prepared polycrystalline samples of the trimer Ir oxide BaIrO3 with
face-shared Ir3O12 trimers, and have investigated the origin of the phase
transition at 182 K by measuring resistivity, thermopower, magnetization and
synchrotron x-ray diffraction. We propose a possible electronic model and
transition mechanism, starting from a localized electron picture on the basis
of the Rietveld refinement. Within this model, BaIrO3 can be basically regarded
as a Mott insulator, when the Ir3O12 trimer is identified to one pseudo-atom or
one lattice site. The transition can be viewed as a transition from the Mott
insulator phase to a kind of charge ordered insulator phase.Comment: 8 pages 5 figures, Crystals (in press
Star-Forming Galaxies at z=0.24 in the Subaru Deep Field and the Sloan Digital Sky Survey
We make a search for Halpha emitting galaxies at z=0.24 in the Subaru Deep
Field (SDF) using the archival data set obtained with the Subaru Telescope. We
carefully select Halpha emitters in the narrowband filter NB816, using B, V,
Rc, i', and z' broad-band colors. We obtain a sample of 258 emitting galaxies
with observed equivalent widths of (Halpha+[NII]6548,6584) greater than 12
angstrom. We also analyze a sample of Halpha emitters taken from the Sloan
Digital Sky Survey (SDSS) to constrain the luminous end of Halpha luminosity
function. Using the same selection criteria as for the SDF, and after excluding
AGNs, we obtain 317 Halpha emitting star-forming galaxies. Combining these two
samples of Halpha emitters found in both SDF and SDSS, we derive a Halpha
luminosity function with best-fit Schechter function parameters of alpha =
-1.31^+0.17_-0.17, log phi^* = -2.46^+0.34_-0.40 Mpc^-3, log L^* =
41.99^+0.08_-0.07 ergs s^-1. An extinction-corrected Halpha luminosity density
is 4.45^+2.96_-1.75 x 10^39 ergs s^-1 Mpc^-3. Using the Kennicutt relation
between the Halpha luminosity and star formation rate, the star formation rate
density in the survey volume is estimated as 0.035^+0.024_-0.014 M_sun yr^-1
Mpc^-3. The angular two-point correlation function of Halpha emitters over 875
arcmin^2 at z = 0.24 is well fitted by a power-law form with w(theta) =
0.047^+0.017_-0.013 theta^-0.66 +- 0.08, corresponding to the correlation
function of xi(r) = (r/2.6^+1.0_-0.8 Mpc)^(-1.66 +- 0.08). The small
correlation length of Halpha emitters may imply the weak clustering of active
star-forming galaxies.Comment: 22 pages, 10 figures, PASJ, Vol.60, No.6 in pres
New Supporting Evidence for the Overdensity of Galaxies around the Radio-Loud Quasar SDSS J0836+0054 at z =5.8
Recently, Zheng et al. (2005) found evidence for an overdensity of galaxies
around a radio-loud quasar, SDSS J0836+0054, at z=5.8 (a five arcmin
region). We have examined our deep optical imaging data (B, V, r', i', z', and
NB816) taken with the Suprime-Cam on the Subaru Telescope. The NB816
narrow-band filter (lambda_c = 815 nm and nm) is suitable
for searching for Ly emitters at . We have found a new
strong Ly emitter at close to object B identified by
Zheng et al. Further, the non detection of the nine objects selected by Zheng
et al. (2005) in our B, V, and r' images provides supporting evidence that they
are high-z objects.Comment: 5 pages, 1 figure, accepted for PAS
Strong Emission-Line Galaxies at Low Redshift in the Field around the Quasar SDSSp J104433.04-012502.2
We discuss observational properties of strong emission-line galaxies at low
redshift found by our deep imaging survey for high-redshift Ly alpha emitters.
In our surveys, we used the narrowband filter, NB816 (lambda_center=8150A with
FWHM = 120A), and the intermediate-band filter, IA827 (lambda_center = 8270A
with FWHM = 340A). In this survey, 62 NB816-excess (> 0.9 mag) and 21
IA827-excess (> 0.8 mag) objects were found. Among them, we found 20
NB816-excess and 4 IA827-excess Ly alpha emitter candidates. Therefore, it
turns out that 42 NB816-excess and 17 IA827-excess objects are strong
emission-line objects at lower redshift. Since 4 objects in the two low-z
samples are common, the total number of strong low-z emitters is 55. Applying
our photometric redshift technique, we identify 7 H alpha emitters at z~0.24,
20 H beta-[OIII] ones at z~0.65, and 11 [OII] ones at z~1.19. However, we
cannot determine reliable photometric redshifts of the remaining 17 emitters.
The distributions of their rest frame equivalent widths are consistently
understood with recent studies of galaxy evolution from z~1 to z~0.Comment: 28 pages, 8 figures, PASJ, Vol. 58, No. 1, in pres
Observation of a Highly Spin Polarized Topological Surface State in GeBiTe
Spin polarization of a topological surface state for GeBiTe, the
newly discovered three-dimensional topological insulator, has been studied by
means of the state of the art spin- and angle-resolved photoemission
spectroscopy. It has been revealed that the disorder in the crystal has a minor
effect on the surface state spin polarization and it exceeds 75% near the Dirac
point in the bulk energy gap region (180 meV). This new finding for
GeBiTe promises not only to realize a highly spin polarized surface
isolated transport but to add new functionality to its thermoelectric and
thermomagnetic properties.Comment: 5 pages, 4 figure
The gigantic Rashba effect of surface states energetically buried in the topological insulator Bi2Te2Se
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.We have clarified that a topological insulator, Bi2Te 2Se, shows two surface states with gigantic Rashba-type spin-splitting located at a binding energy deeper than the topological surface state. The magnitude of the Rashba parameter, as well as the momentum splitting, is found to be large enough to realize a number of nanometer-sized spintronic devices. This novel finding paves the way to studies of gigantic Rashba systems that are suitable for future spintronic applications. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.A portion of this work has been done under the Japan–Russia Bilateral Joint Research Project (JSPS). This work was financially supported by KAKENHI (grant nos. 23340105, 23244066, 25800179), Grant-in-Aid for Scientific Research (A), (B) and for Young Scientists (B) of JSPS. KAK and OET acknowledge financial support by the RFBR (grant nos. 13-02-92105 and 12-02-00226), and by the Ministry of Education and Science of the Russian Federation.Peer Reviewe
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