2,387 research outputs found
Excitation Induced Dephasing in Semiconductor Quantum Dots
A quantum kinetic theory is used to compute excitation induced dephasing in
semiconductor quantum dots due to the Coulomb interaction with a continuum of
states, such as a quantum well or a wetting layer. It is shown that a frequency
dependent broadening together with nonlinear resonance shifts are needed for a
microscopic explanation of the excitation induced dephasing in such a system,
and that excitation induced dephasing for a quantum-dot excitonic resonance is
different from quantum-well and bulk excitons.Comment: 6 pages, 4 figures. Extensively revised text, two figures change
Mid-career mentoring and capacity building strategies: A path to professional development and career advancement
This poster describes the progress and lessons learned as a result of newly implemented Faculty Mentoring Program in the IU School of Social Work
Peripheral Nucleon-Nucleon Phase Shifts and Chiral Symmetry
Within the one-loop approximation of baryon chiral perturbation theory we
calculate all one-pion and two-pion exchange contributions to the
nucleon-nucleon interaction. In fact we construct the elastic NN-scattering
amplitude up to and including third order in small momenta. The phase shifts
with orbital angular momentum and the mixing angles with are
given parameterfree and thus allow for a detailed test of chiral symmetry in
the two-nucleon system. We find that for the D-waves the -exchange
corrections are too large as compared with empirical phase shifts, signaling
the increasing importance of shorter range effects in lower partial waves. For
higher partial waves, especially for G-waves, the model independent
-exchange corrections bring the chiral prediction close to empirical NN
phase shifts. We propose to use the chiral NN phase shifts with as
input in a future phase shift analysis. Furthermore, we compute the irreducible
two-pion exchange NN-potentials in coordinate space. They turn out to be of
van-der-Waals type, with exponential screening of two-pion mass range.Comment: 30 pages, TeX,12 figures in ps , submitted to Nucl. Phys.
Domain walls in (Ga,Mn)As diluted magnetic semiconductor
We report experimental and theoretical studies of magnetic domain walls in an
in-plane magnetized (Ga,Mn)As dilute moment ferromagnetic semiconductor. Our
high-resolution electron holography technique provides direct images of domain
wall magnetization profiles. The experiments are interpreted based on
microscopic calculations of the micromagnetic parameters and
Landau-Lifshitz-Gilbert simulations. We find that the competition of uniaxial
and biaxial magnetocrystalline anisotropies in the film is directly reflected
in orientation dependent wall widths, ranging from approximately 40 nm to 120
nm. The domain walls are of the N\'eel type and evolve from near-
walls at low-temperatures to large angle [10]-oriented walls and small
angle [110]-oriented walls at higher temperatures.Comment: 5 pages, 4 figure
Exotic Heavy Fermion State in the Filled Skutterudite PrFeP Uncovered by the de Haas-van Alphen Effect
We report the de Haas-van Alphen (dHvA) experiment on the filled skutterudite
PrFeP exhibiting apparent Kondo-like behaviors in the transport and
thermal properties. We have found enormously enhanced cyclotron effective mass
in the high field phase (HFP), which
indicates that PrFeP is the first Pr-compound in which really heavy
mass has been unambiguously confirmed. Also in the low field non-magnetic
ordered phase (LOP), we observed the dHvA branch with that is quite heavy taking into account its small Fermi surface volume
(0.15% of the Brillouin zone size). The insensitivity of mass in LOP against
the magnetic field suggests that the quadrupolar interaction plays a main role
both in the mass renormalization and the LOP formation.Comment: 5 pages, 5 figures, Phys. Rev. B (01 October 2002) in pres
Thermodynamics of Superstring on Near-extremal NS5 and Effective Hagedorn Behavior
We study the thermodynamical torus partition function of superstring on the
near-extremal black NS5-brane background. The exact partition function has been
computed with the helps of our previous works:[arXiv:1012.5721 [hep-th]],
[arXiv:1109.3365 [hep-th]], and naturally decomposed into two parts. The first
part is contributed from strings freely propagating in the asymptotic region,
which are identified as the superstring gas at the Hawking temperature on the
linear-dilaton background. The second part includes the contribution localized
around the `tip of cigar', which characterizes the non-extremality. Remarkably,
the latter part includes massless excitations with non-vanishing thermal
winding, which signifies that the Hagedorn-like behavior effectively appears,
even though the Hawking temperature is much lower than the Hagedorn
temperature. We also explore the high-temperature backgrounds defined by the
orbifolding along the Euclidean time direction. In those cases, the thermal
winding modes localized around the tip are found to be tachyonic, reflecting
the singularities of Euclidean backgrounds caused by orbifolding.Comment: 1+29 pages, no figure; v2 the footnote 1 is enhanced, to appear in
JHE
Self-Interaction and Gauge Invariance
A simple unified closed form derivation of the non-linearities of the
Einstein, Yang-Mills and spinless (e.g., chiral) meson systems is given. For
the first two, the non-linearities are required by locality and consistency; in
all cases, they are determined by the conserved currents associated with the
initial (linear) gauge invariance of the first kind. Use of first-order
formalism leads uniformly to a simple cubic self-interaction.Comment: Missing last reference added. 9 pages, This article, the first paper
in Gen. Rel. Grav. [1 (1970) 9], is now somewhat inaccessible; the present
posting is the original version, with a few subsequent references included.
Updates update
Time-Reversal Symmetry-Breaking Superconductivity in Heavy Fermion PrOs4Sb12 detected by Muon Spin Relaxation
We report on muon spin relaxation measurements of the 4f^2-based
heavy-fermion superconductor filled-skutterudite PrOs4Sb12. The results reveal
the spontaneous appearance of static internal magnetic fields below the
superconducting transition temperature, providing unambiguous evidence for the
breaking of time-reversal symmetry in the superconducting state. A discussion
is made on which of the spin or orbital component of Cooper pairs carries a
nonzero momentum.Comment: 5 pages with 3 figure
Unusual behaviors in the transport properties of REFeP (RE: La, Ce, Pr, and Nd)
We have investigated the resistivity (), thermoelectric power (TEP) and
Hall coefficient () on high quality single crystals of
REFeP. TEP in CeFeP is extremely large (
0.5mV/K at 290K) with a peak of 0.75mV/K at around 65K. The Hall
mobility also shows a peak at 65K, suggesting carriers with heavy masses
developed at lower temperatures related with the f-hybridized band. Both Pr-
and Nd- systems exhibit an apparent increase of with decreasing
temperature far above their magnetic transition temperatures. In the same
temperature ranges, TEP exhibits unusually large absolute values of -50V/K
for PrFeP and -15V/K for NdFeP, respectively.
For PrFeP, such anomalous transport properties suggest an unusual
ground state, possibly related with the Quadrupolar Kondo effect.Comment: 5 pages, 8 figure
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