543 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
Characterization of the free-carrier concentrations in doped β-SiC crystals by Raman scattering
Interstellar Gas and X-rays toward the Young Supernova Remnant RCW 86; Pursuit of the Origin of the Thermal and Non-Thermal X-ray
We have analyzed the atomic and molecular gas using the 21 cm HI and 2.6/1.3
mm CO emissions toward the young supernova remnant (SNR) RCW 86 in order to
identify the interstellar medium with which the shock waves of the SNR
interact. We have found an HI intensity depression in the velocity range
between and km s toward the SNR, suggesting a cavity in the
interstellar medium. The HI cavity coincides with the thermal and non-thermal
emitting X-ray shell. The thermal X-rays are coincident with the edge of the HI
distribution, which indicates a strong density gradient, while the non-thermal
X-rays are found toward the less dense, inner part of the HI cavity. The most
significant non-thermal X-rays are seen toward the southwestern part of the
shell where the HI gas traces the dense and cold component. We also identified
CO clouds which are likely interacting with the SNR shock waves in the same
velocity range as the HI, although the CO clouds are distributed only in a
limited part of the SNR shell. The most massive cloud is located in the
southeastern part of the shell, showing detailed correspondence with the
thermal X-rays. These CO clouds show an enhanced CO = 2-1/1-0 intensity
ratio, suggesting heating/compression by the shock front. We interpret that the
shock-cloud interaction enhances non-thermal X-rays in the southwest and the
thermal X-rays are emitted by the shock-heated gas of density 10-100 cm.
Moreover, we can clearly see an HI envelope around the CO cloud, suggesting
that the progenitor had a weaker wind than the massive progenitor of the
core-collapse SNR RX J1713.73949. It seems likely that the progenitor of RCW
86 was a system consisting of a white dwarf and a low-mass star with
low-velocity accretion winds.Comment: 19 pages, 15 figures, 4 tables, accepted for publication in Journal
of High Energy Astrophysics (JHEAp
Spatially Resolved [FeII] 1.64 \mu m Emission in NGC 5135. Clues for Understanding the Origin of the Hard X-rays in Luminous Infrared Galaxies
Spatially resolved near-IR and X-ray imaging of the central region of the
Luminous Infrared Galaxy NGC 5135 is presented. The kinematical signatures of
strong outflows are detected in the [FeII]1.64 \mu m emission line in a compact
region at 0.9 kpc from the nucleus. The derived mechanical energy release is
consistent with a supernova rate of 0.05-0.1 yr. The apex of the
outflowing gas spatially coincides with the strongest [FeII] emission peak and
with the dominant component of the extranuclear hard X-ray emission. All these
features provide evidence for a plausible direct physical link between
supernova-driven outflows and the hard X-ray emitting gas in a LIRG. This
result is consistent with model predictions of starbursts concentrated in small
volumes and with high thermalization efficiencies. A single high-mass X-ray
binary (HMXB) as the major source of the hard X-ray emission although not
favoured, cannot be ruled out. Outside the AGN, the hard X-ray emission in NGC
5135 appears to be dominated by the hot ISM produced by supernova explosions in
a compact star-forming region, and not by the emission due to HMXB. If this
scenario is common to U/LIRGs, the hard X-rays would only trace the most
compact (< 100 pc) regions with high supernova and star formation densities,
therefore a lower limit to their integrated star formation. The SFR derived in
NGC 5135 based on its hard X-ray luminosity is a factor of two and four lower
than the values obtained from the 24 \mu m and soft X-ray luminosities,
respectively.Comment: Accepted for Publication in ApJ, 18 pages, 2 figure
Angiotensin II Reduces Mitochondrial Content in Skeletal Muscle and Affects Glycemic Control
OBJECTIVE—Blockade of angiotensin (Ang) II has been shown to prevent new-onset type 2 diabetes. We focused on the effects of AngII on muscle mitochondria, especially on their biogenesis, as an underlining mechanism of type 2 diabetes
Composition Control of Electron Beam Induced Nanodeposits by Surface Pretreatment and Beam Focusing
Orientation and symmetries of Alexandrov spaces with applications in positive curvature
We develop two new tools for use in Alexandrov geometry: a theory of ramified
orientable double covers and a particularly useful version of the Slice Theorem
for actions of compact Lie groups. These tools are applied to the
classification of compact, positively curved Alexandrov spaces with maximal
symmetry rank.Comment: 34 pages. Simplified proofs throughout and a new proof of the Slice
Theorem, correcting omissions in the previous versio
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