594 research outputs found
Linear response calculation using the canonical-basis TDHFB with a schematic pairing functional
A canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov
(TDHFB) theory is obtained with an approximation that the pair potential is
assumed to be diagonal in the time-dependent canonical basis. The
canonical-basis formulation significantly reduces the computational cost. We
apply the method to linear-response calculations for even-even nuclei. E1
strength distributions for proton-rich Mg isotopes are systematically
calculated. The calculation suggests strong Landau damping of giant dipole
resonance for drip-line nuclei.Comment: 6 pages, 1 figure, INPC 2010 conference proceding
Chemical potential shift induced by double-exchange and polaronic effects in Nd_{1-x}Sr_xMnO_3
We have studied the chemical potential shift as a function of temperature in
NdSrMnO (NSMO) by measurements of core-level photoemission
spectra. For ferromagnetic samples ( and 0.45), we observed an unusually
large upward chemical potential shift with decreasing temperature in the
low-temperature region of the ferromagnetic metallic (FM) phase. This can be
explained by the double-exchange (DE) mechanism if the band is split by
dynamical/local Jahn-Teller effect. The shift was suppressed near the Curie
temperature (), which we attribute to the crossover from the DE to
lattice-polaron regimes.Comment: 5 pages, 6 figure
Depth profile photoemission study of thermally diffused Mn/GaAs (001) interfaces
We have performed a depth profile study of thermally diffused Mn/GaAs (001)
interfaces using photoemission spectroscopy combined with Ar-ion
sputtering. We found that Mn ion was thermally diffused into the deep region of
the GaAs substrate and completely reacted with GaAs. In the deep region, the Mn
2 core-level and Mn 3 valence-band spectra of the Mn/GaAs (001) sample
heated to 600 C were similar to those of GaMnAs,
zinc-blende-type MnAs dots, and/or interstitial Mn in tetrahedrally coordinated
by As atoms, suggesting that the Mn 3 states were essentially localized but
were hybridized with the electronic states of the host GaAs. Ferromagnetism was
observed in the dilute Mn phase.Comment: 5 pages, 4 figure
Chemical potential shift and spectral weight transfer in PrCaMnO revealed by photoemission spectroscopy
We have studied the chemical potential shift and changes in the electronic
density of states near the Fermi level () as a function of carrier
concentration in PrCaMnO (PCMO, ) through
the measurements of photoemission spectra. The results showed that the chemical
potential shift was suppressed for x \agt 0.3, where the charge exchange
(CE)-type antiferromagnetic charge-ordered state appears at low temperatures.
We consider this observation to be related to charge self-organization such as
stripe formation on a microscopic scale in this composition range. Together
with the previous observation of monotonous chemical potential shift in
LaSrMnO, we conclude that the tendency toward the charge
self-organization increases with decreasing bandwidth. In the valence band,
spectral weight of the Mn 3 electrons in PCMO was transferred from
1 eV below to the region near with hole doping, leading to a
finite intensity at even in the paramagnetic insulating phase for x \agt
0.3, probably related with the tendency toward charge self-organization. The
finite intensity at in spite of the insulating transport behavior is
consistent with fluctuations involving ferromagnetic metallic states.Comment: 6 pages, 5 figure
Cold SO_2 molecules by Stark deceleration
We produce SO_2 molecules with a centre of mass velocity near zero using a
Stark decelerator. Since the initial kinetic energy of the supersonic SO_2
molecular beam is high, and the removed kinetic energy per stage is small, 326
deceleration stages are necessary to bring SO_2 to a complete standstill,
significantly more than in other experiments. We show that in such a
decelerator possible loss due to coupling between the motional degrees of
freedom must be considered. Experimental results are compared with 3D
Monte-Carlo simulations and the quantum state selectivity of the Stark
decelerator is demonstrated.Comment: 7 pages, 5 figure
Linear Responses in Time-dependent Hartree-Fock-Bogoliubov Method with Gogny Interaction
A numerical method to integrate the time-dependent Hartree-Fock Bogoliubov
(TDHFB) equations with Gogny interaction is proposed. The feasibility of the
TDHFB code is illustrated by the conservation of the energy, particle numbers,
and center-of-mass in the small amplitude vibrations of oxygen 20. The TDHFB
code is applied to the isoscalar quadrupole and/or isovector dipole vibrations
in the linear (small amplitude) region in oxygen isotopes (masses A = 18,20,22
and 24), titanium isotopes (A = 44,50,52 and 54), neon isotope (A = 26), and
magnesium isotopes (A = 24 and 34). The isoscalar quadrupole and isovector
dipole strength functions are calculated from the expectation values of the
isoscalar quadrupole and isovector dipole moments.Comment: 10 pages, 13 figure
Representation of Neck Velocity and Neck–Vestibular Interactions in Pursuit Neurons in the Simian Frontal Eye Fields
The smooth pursuit system must interact with the vestibular system to maintain the accuracy of eye movements in space (i.e., gaze-movement) during head movement. Normally, the head moves on the stationary trunk. Vestibular signals cannot distinguish whether the head or whole body is moving. Neck proprioceptive inputs provide information about head movements relative to the trunk. Previous studies have shown that the majority of pursuit neurons in the frontal eye fields (FEF) carry visual information about target velocity, vestibular information about whole-body movements, and signal eye- or gaze-velocity. However, it is unknown whether FEF neurons carry neck proprioceptive signals. By passive trunk-on-head rotation, we tested neck inputs to FEF pursuit neurons in 2 monkeys. The majority of FEF pursuit neurons tested that had horizontal preferred directions (87%) responded to horizontal trunk-on-head rotation. The modulation consisted predominantly of velocity components. Discharge modulation during pursuit and trunk-on-head rotation added linearly. During passive head-on-trunk rotation, modulation to vestibular and neck inputs also added linearly in most neurons, although in half of gaze-velocity neurons neck responses were strongly influenced by the context of neck rotation. Our results suggest that neck inputs could contribute to representing eye- and gaze-velocity FEF signals in trunk coordinates
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