3,843 research outputs found
Ultrafast nematic-orbital excitation in FeSe
The electronic nematic phase is an unconventional state of matter that
spontaneously breaks the rotational symmetry of electrons. In
iron-pnictides/chalcogenides and cuprates, the nematic ordering and
fluctuations have been suggested to have as-yet-unconfirmed roles in
superconductivity. However, most studies have been conducted in thermal
equilibrium, where the dynamical property and excitation can be masked by the
coupling with the lattice. Here we use femtosecond optical pulse to perturb the
electronic nematic order in FeSe. Through time-, energy-, momentum- and
orbital-resolved photo-emission spectroscopy, we detect the ultrafast dynamics
of electronic nematicity. In the strong-excitation regime, through the
observation of Fermi surface anisotropy, we find a quick disappearance of the
nematicity followed by a heavily-damped oscillation. This short-life nematicity
oscillation is seemingly related to the imbalance of Fe 3dxz and dyz orbitals.
These phenomena show critical behavior as a function of pump fluence. Our
real-time observations reveal the nature of the electronic nematic excitation
instantly decoupled from the underlying lattice
Size variance of motor evoked potential at initiation of voluntary contraction in palsy of conversion disorder
ArticlePSYCHIATRY AND CLINICAL NEUROSCIENCES. 62(3): 286-292(2008)journal articl
Three-dimensional bulk band dispersion in polar BiTeI with giant Rashba-type spin splitting
In layered polar semiconductor BiTeI, giant Rashba-type spin-split band
dispersions show up due to the crystal structure asymmetry and the strong
spin-orbit interaction. Here we investigate the 3-dimensional (3D) bulk band
structures of BiTeI using the bulk-sensitive -dependent soft x-ray angle
resolved photoemission spectroscopy (SX-ARPES). The obtained band structure is
shown to be well reproducible by the first-principles calculations, with huge
spin splittings of meV at the conduction-band-minimum and
valence-band-maximum located in the plane. It provides the first
direct experimental evidence of the 3D Rashba-type spin splitting in a bulk
compound.Comment: 9 pages, 4 figure
Strongly spin-orbit coupled two-dimensional electron gas emerging near the surface of polar semiconductors
We investigate the two-dimensional (2D) highly spin-polarized electron
accumulation layers commonly appearing near the surface of n-type polar
semiconductors BiTeX (X = I, Br, and Cl) by angular-resolved photoemission
spectroscopy. Due to the polarity and the strong spin-orbit interaction built
in the bulk atomic configurations, the quantized conduction-band subbands show
giant Rashba-type spin-splitting. The characteristic 2D confinement effect is
clearly observed also in the valence-bands down to the binding energy of 4 eV.
The X-dependent Rashba spin-orbit coupling is directly estimated from the
observed spin-split subbands, which roughly scales with the inverse of the
band-gap size in BiTeX.Comment: 15 pages 4 figure
Orbital-dependent modifications of electronic structure across magneto-structural transition in BaFe2As2
Laser angle-resolved photoemission spectroscopy (ARPES) is employed to
investigate the temperature (T) dependence of the electronic structure in
BaFe2As2 across the magneto-structural transition at TN ~ 140 K. A drastic
transformation in Fermi surface (FS) shape across TN is observed, as expected
by first-principles band calculations. Polarization-dependent ARPES and band
calculations consistently indicate that the observed FSs at kz ~ pi in the
low-T antiferromagnetic (AF) state are dominated by the Fe3dzx orbital, leading
to the two-fold electronic structure. These results indicate that
magneto-structural transition in BaFe2As2 accompanies orbital-dependent
modifications in the electronic structure.Comment: 13 pages, 4 figures. accepted by Physical Review Letter
Phenotypical analysis of lymphocytes using flow cytometry in dermatomyositis with and without interstitial pneumonia
ArticleJOURNAL OF NEUROIMMUNOLOGY. 178 Supple 1. 233 (2006)journal articl
Therapeutic outcome of cyclic VAD (vincristine, doxorubicin and dexamethasone) therapy in primary systemic AL amyloidosis patients
ArticleINTERNAL MEDICINE. 47(17):1517-1522(2008)journal articl
Origin of the Weak Pseudo-gap Behaviors in Na_{0.35}CoO_2: Absence of Small Hole Pockets
We analyze the ``normal electronic states'' of Na_{0.35}CoO_2 based on the
effective d-p model with full d-orbital freedom using the fluctuation-exchange
(FLEX) approximation. They sensitively depend on the topology of the Fermi
surfaces, which changes as the crystalline electric splitting (CES) due to the
trigonal deformation. We succeed in reproducing the weak pseudo-gap behaviors
in the density of states (DOS) and in the uniform magnetic susceptibility below
300K, assuming that six small hole-pockets predicted by LDA band calculations
are absent. When they exist, on the contrary, then ``anti-pseudo-gap
behaviors'' should inevitably appear. Thus, the present study strongly supports
the absence of the small hole-pockets in Na_{0.35}CoO_2, as reported by recent
ARPES measurements. A large Fermi surface around the \Gamma-point would account
for the superconductivity in water-intercalated samples.Comment: 5pages, to appear in J. Phys. Soc. Jpn. Vol.74 (2005) No.
"Pudding mold" band drives large thermopower in NaCoO
In the present study, we pin down the origin of the coexistence of the large
thermopower and the large conductivity in NaCoO. It is revealed that
not just the density of states (DOS), the effective mass, nor the band width,
but the peculiar {\it shape} of the band referred to as the "pudding
mold" type, which consists of a dispersive portion and a somewhat flat portion,
is playing an important role in this phenomenon. The present study provides a
new guiding principle for designing good thermoelectric materials.Comment: 5 page
Phylogeny of Galactolipid Synthase Homologs Together with their Enzymatic Analyses Revealed a Possible Origin and Divergence Time for Photosynthetic Membrane Biogenesis
The photosynthetic membranes of cyanobacteria and chloroplasts of higher plants have remarkably similar lipid compositions. In particular, thylakoid membranes of both cyanobacteria and chloroplasts are composed of galactolipids, of which monogalactosyldiacylglycerol (MGDG) is the most abundant, although MGDG biosynthetic pathways are different in these organisms. Comprehensive phylogenetic analysis revealed that MGDG synthase (MGD) homologs of filamentous anoxygenic phototrophs Chloroflexi have a close relationship with MGDs of Viridiplantae (green algae and land plants). Furthermore, analyses for the sugar specificity and anomeric configuration of the sugar head groups revealed that one of the MGD homologs exhibited a true MGDG synthetic activity. We therefore presumed that higher plant MGDs are derived from this ancestral type of MGD genes, and genes involved in membrane biogenesis and photosystems have been already functionally associated at least at the time of Chloroflexi divergence. As MGD gene duplication is an important event during plastid evolution, we also estimated the divergence time of type A and B MGDs. Our analysis indicated that these genes diverged ∼323 million years ago, when Spermatophyta (seed plants) were appearing. Galactolipid synthesis is required to produce photosynthetic membranes; based on MGD gene sequences and activities, we have proposed a novel evolutionary model that has increased our understanding of photosynthesis evolution
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