pinecone/core-2020-05-10-deduplication huggingface dataset:
On the symmetry of a Preisach map

At the very heart of the successful phenomenological model of magnetic
hysteresis there is the so called Preisach distribution. In the existing
literature it is implicitly assumed, that this distribution has a mirror
symmetry. We show, by simple and convincing example, that this common
assumption is plainly wrong. Dropping it, we gain the ability to model not only
the usual hysteresis loops (major and minor) more accurately than ever before,
but also those displaying the exchange bias effect, what is impossible within
the framework of the symmetrical Preisach model. It is hoped, that our
observation paves the way towards the unified description of all the hysteretic
systems, including, but not necessarily limited to, superconductors,
(multi)layered structures, nanocrystalline materials, patterned media, and -
perhaps - the other non-magnetic hysteretic phenomena.Comment: 4 pages, 2 figures. Presented at the European Conference "Physics of
  Magnetism'05", Poznan (Poland), June 24-27, 2005. Accepted for publication in
  physica status solidi (b) (C) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei
Temperature effects in a spin-orbital model for manganites

We study a two-dimensional effective orbital superexchange model derived for
strongly correlated e_g electrons coupled to t_{2g} core spins in layered
manganites. One finds that the ferromagnetic and antiferromagnetic correlations
closely compete, and small changes of parameters can switch the type of
magnetic order. For the same reason, spin order is easily destroyed with rising
temperature, while alternating orbital correlations can persist to temperatures
where FM order has already melted. A scenario for the AF phase observed in
LaSrMnO_4 is presented.Comment: 4 pages, 3 figures, contribution to the PM05-meeting in Poznan,
  Polan
Competition of ferromagnetism and superconductivity in Sc3InB

We present results of electronic structure calculations for intermetallic
perovskite Sc3InB with Full--Potential KKR-LDA method. Sc3InB is very promising
candidate for a new superconductor (related to 8K MgCNi3) and can be regarded
as a boron-inserted cubic Sc3In, which is a high--pressure allotropic form of
the hexagonal weak ferromagnet Sc3In. We predict that cubic Sc3In can be also
magnetic, whereas Sc3InB having large DOS in the vicinity of EF exhibits
non-magnetic ground state. Estimation of the electron--phonon coupling for
Sc3InB gives $\lambda \simeq 1$. Furthermore, the effect of vacancy in
Sc3InB{1-x} and antisite disorder in Sc3(In-B) on critical parameters is also
discussed in view of KKR--CPA method. All theoretical results support
possibility of the superconductivity onset in Sc3InB. Preliminary experimental
measurements established the transition temperature close to 4.5 K, with a very
abrupt change in susceptibility and a correlated drop of the resistivity when
cooling down.Comment: 4 pages, 3 figures. Conference Paper, presented at European
  Conference Physics of Magnetism'05, 24-27.06.2005, Poznan, POLAND. Reference
  correcte
Sequence Dependence of Electronic Transport in DNA

We study electronic transport in long DNA chains using the tight-binding
approach for a ladder-like model of DNA. We find insulating behavior with
localizaton lengths xi ~ 25 in units of average base-pair seperation.
Furthermore, we observe small, but significant differences between lambda-DNA,
centromeric DNA, promoter sequences as well as random-ATGC DNA.Comment: 4 pages, 1 figure, Proceedings of "Transport in Interacting and
  Disordered Systems (TIDS11)", accepted for publication in phys. stat. sol.
  (b/c), including pss style file
Spin-Hall effect in semiconductor heterostructures with cubic Rashba
  spin-orbit interaction

We study the spin-Hall effect in systems with weak cubic Rashba spin-orbit
interaction. To this end we derive particle and spin diffusion equations and
explicit expressions for the spin-current tensor in the diffusive regime. We
discuss the impact of electric fields on the Green's functions and the
diffusion equations and establish a relationship between the spin-current
tensor and the spin diffusion equations for the model under scrutiny. We use
our results to calculate the edge spin-accumulation in a spin-Hall experiment
and show that there is also a new Hall-like contribution to the electric
current in such systems.Comment: 14 page
Unintentionally doped InN grown onto an atomically flat AlN intermediate layer using plasma-assisted molecular beam epitaxy

[[abstract]]Unintentionally doped InN has been grown onto an atomically flat AlN intermediate layer on top of the Si(111) substrate using plasma-assisted molecular beam epitaxy (PA-MBE). Though there are lots of micrometer-size indium droplets randomly distributed on the top of the surface, the highest electron mobility of this InN thin film measured at room temperature by van der Pauw method is still higher than 1000 cm2/V s with a carrier concentration of 5-8.9 ?1018 cm-3. A symmetrical X-ray rocking curve is measured and the full-width-at-half-maximum (FWHM) of this sample is 1089 arcsec. In the meantime, the threading dislocation (TD) density of this material is estimated to around 9.8 ?108 cm-2 - 7.5 ?109 cm-2 depending on the probing regions that are studied by the etching technique and field-emission scanning electron microscopy (FE-SEM). (2 ?1) in situ reflection high-energy electron diffraction (RHEED) patterns show that this sample is grown under In-rich environment with possible In-terminated surface. From the FE-SEM pictures which were taken from the samples after 10 minutes etching in hydrochloride, the surface morphology shows In-polarity-like patterns that coincide with those procured in RHEED. To select and grow a high-quality laminated AlN as intermediate layer is believed to be the major step in obtaining this high electron mobility InN thin film on Si substrate.[[fileno]]2020305010012[[department]]材料科學工程學
Non-finite-difference algorithm for integrating Newton's motion
  equations

We have presented some practical consequences on the molecular-dynamics
simulations arising from the numerical algorithm published recently in paper
Int. J. Mod. Phys. C 16, 413 (2005). The algorithm is not a finite-difference
method and therefore it could be complementary to the traditional numerical
integrating of the motion equations. It consists of two steps. First, an
analytic form of polynomials in some formal parameter $\lambda$ (we put
$\lambda=1$ after all) is derived, which approximate the solution of the system
of differential equations under consideration. Next, the numerical values of
the derived polynomials in the interval, in which the difference between them
and their truncated part of smaller degree does not exceed a given accuracy
$\epsilon$, become the numerical solution. The particular examples, which we
have considered, represent the forced linear and nonlinear oscillator and the
2D Lennard-Jones fluid. In the latter case we have restricted to the
polynomials of the first degree in formal parameter $\lambda$.
  The computer simulations play very important role in modeling materials with
unusual properties being contradictictory to our intuition. The particular
example could be the auxetic materials. In this case, the accuracy of the
applied numerical algorithms as well as various side-effects, which might
change the physical reality, could become important for the properties of the
simulated material.Comment: 11 page
Anisotropic properties of mechanical characteristics and auxeticity of
  cubic crystalline media

Explicit expressions for inverse of Young's modulus E, inverse of shear
modulus G, and Poisson's ratio for cubic media are considered. All these
characteristics of elastic media depend on three components of the compliance
tensor S, and on direction cosines of mutually perpendicular vectors m and n
with fourfold symmetry axes. These characteristics are studied for all
mechanically stable cubic materials for vectors n belonging to the irreducible
body angle subtended by three cubic high symmetry directions [001], [111], and
[110]. Regions in the stability triangle of in which cubic elastic materials
are completely auxetic, non-auxetic, and auxetic are established. Several
intermediate-valence compounds belonging to the region of complete auxecity are
indicated. The extreme properties of E^{-1}, G^{-1} and Poisson ratio
established by Hayes and Shuvalov are confirmed.Comment: 16 pages, 8 figures, 2nd Workshop on Auxetics and Related Systems
  Bedlewo (near Poznan), August 19-23, 200
Young's and shear moduli and Poisson's ratio for elastic media of high
  and middle symmetry

Using bases of fourth rank tensorial bases of complete Voigt's symmetry
elaborated by Walpole we obtained expressions for inverse of Young's modulus E,
inverse of shear modulus G and Poisson's ratio, which depend on components of
the stiffness tensor S, on direction cosines of vectors n of uniaxial load and
the vector m of lateral strain with crystalline symmetry axes. Crystalline
media of high and medium symmetries are considered. Such representation yields
decomposition of the above elastic characteristics to isotropic and anisotropic
parts. Expressions for Poisson's coefficient are well suited for studying the
property of auxeticity.Comment: 14 pages, no figures, 2nd Workshop on Auxetics and Related Systems
  Bedlewo (near Poznan), August 19-23, 200
Weak universal critical behaviour of the mixed spin-(1/2, S) Ising model
  on the union jack (centered square) lattice: integer versus half-odd-integer
  spin-S case

The mixed spin-(1/2, S) Ising model on the union jack (centered square)
lattice is investigated by establishing the mapping relationship with its
corresponding eight-vertex model. An interplay between the nearest-neighbour
interaction, the competing next-nearest-neighbour interaction and the
single-ion anisotropy gives rise to a rather complex critical behaviour
displayed in the reentrant phase transitions, the weak universal critical
behaviour, as well as, a presence of first- and second-order phase transitions.
The most interesting finding to emerge from the present study relates to a
variation of the weak-universal critical exponents along the line of bicritical
points, which is being twice as large for the mixed spin-(1/2, S) systems with
the integer spin-S atoms as for the ones with the half-odd-integer spin-S
atoms.Comment: 9 pages, 12 figure
Diffusion thermopower of a $p-$type Si/Si$_{1-x}$Ge$_x$ heterostructure
  at zero magnetic field

We calculate the diffusion thermopower of the degenerate two-dimensional hole
gas in a $p-$type Si/Si$_{1-x}$Ge$_x$ lattice mismatched heterostructure at low
temperatures and zero magnetic field. The effects of possible scatterings, e.g.
remote impurity, alloy disorder, interface roughness, deformation potential,
and random piezoelectric on the hole mobility and the diffusion thermopower are
examined. Calculated results are well fitted to the experimental data recently
reported. In addition, we predict a possibility for the diffusion thermopower
to change its sign as the SiGe layer thickness changes, the effect has not been
discussed yet.Comment: This is the final version of the preprint arXiv:cond-mat/060381
Geometry dependence of the conductance oscillations of monovalent atomic
  chains

Using a tight binding model we calculate the conductance of monovalent atomic
chains for different contact geometries. The leads connected to the chains are
modelled as semi-infinite fcc lattices with different orientations and
couplings. Our aim is twofold: To check the validity of a three-parametric
conductance formula for differently oriented leads, and to investigate the
geometry dependence of the conductance oscillations. We show that the character
of these oscillations depends strongly on the geometry of the chain-lead
coupling.Comment: 9 pages, 5 figures, 1 tabl
Spin ordering: two different scenarios for the single and double layer
  structures in the fractional and integer quantum Hall effect regimes

We investigate the ground state competition at the transition from the spin
unpolarized to spin ordered phase at filling factor $\nu=2/3$ in single layer
heterostructure and at $\nu=2$ in double layer quantum well. To trace the
quantum Hall phase we use the minimum in the dissipative conductivity
$\sigma_{xx}$. We observe two different transition scenarios in two
investigated situations. For one of them we propose a qualitative explanation,
based on the domain structure evolution in the vicinity of the transition
point. The origin for the second scenario, corresponding to the experimental
situation at $\nu=2$ in double layer 2DES, still remains unclear.Comment: 4 page
Effects of dilution and disorder on magnetism in diluted spin systems

The influence of configurational disorder on the magnetic properties of
diluted Heisenberg spin systems is studied with regard to the ferromagnetic
stability of diluted magnetic semiconductors. The equation of motion of the
magnon Green's function is decoupled by Tyablikov approximation. With supercell
approach, the concentrations of magnetic ions are determined by the size of the
supercell in which there is only one magnetic ion per supercell in our method.
In order to distinguish the influence of dilution and disorder, there are two
kinds of supercells being used: the \textit{diluted and ordered} case and the
\textit{diluted and disordered} case. The configurational averaging of magnon
Green function due to disorder is treated in the augmented space formalism. The
random exchange integrals between two supercells are treated as a matrix. The
obtained magnon spectral densities are used to calculate the temperature
dependence of magnetization and Curie temperature. The results are shown as
following: (i) dilution leads to increasing the averaged distance of two
magnetic ions, further decreases the effective exchange integrals and is main
reason to reduce Curie temperature; (ii) spatial position disorder of magnetic
ions results in the dispersions of the exchange integrals between two
supercells and slightly changes ferromagnetic transition temperature; (iii) the
exponential damping of distance dependence obviously reduces Curie temperature
and should be set carefully in any phenomenological model.Comment: 8 pages, 3 figures, accepted by physica status solidi (b); added
  references and the corresponding remark
Anisotropic and inhomogeneous Coulomb screening in the Thomas-Fermi approximation: Application to quantum dot-wetting layer system and Auger relaxation

International audienceA model for anisotropic and inhomogeneous Coulomb screening due to 2D and 3D carriers, is proposed in the Thomas–Fermi approximation. Analytical expressions for the screened interaction potentials and scattering matrix elements are obtained. This model is applied to the Auger relaxation of carriers in an InAs/InP quantum dot (QD) – wetting layer (WL) system. The influences of the QD morphology and carriers densities on screening and Auger effects are studied. 2D–2D scattering is found to be the most important process, depending especially on QD morphology. A smearing effect is associated to the wetting layer wavefunction extension along the growth axis. The screened potential is similar to a potential screened by 3D carriers
Measurement, control, and decay of quantum-dot spins

In this review we discuss a recent proposal to perform partial Bell-state
(parity) measurements on two-electron spin states for electrons confined to
quantum dots. The realization of this proposal would allow for a physical
implementation of measurement-based quantum computing. In addition, we consider
the primary sources of energy relaxation and decoherence which provide the
ultimate limit to all proposals for quantum information processing using
electron spins in quantum dots. We give an account of the Hamiltonians used for
the most important interactions (spin-orbit and hyperfine) and survey some of
the recent work done to understand dynamics, control, and decoherence under the
action of these Hamiltonians. We conclude the review with a table of important
decay times found in experiment, and relate these time scales to the potential
viability of measurement-based quantum computing.Comment: v1: 15 pages, 1 figure, review article to be published in a special
  issue of physica status solidi (b); v2: added/updated citation list, decay
  times in Table 1, made other minor correction
The on-shell self-energy of the uniform electron gas in its
  weak-correlation limit

The ring-diagram partial summation (or RPA) for the ground-state energy of
the uniform electron gas (with the density parameter $r_s$) in its
weak-correlation limit $r_s\to 0 $ is revisited. It is studied, which treatment
of the self-energy $\Sigma(k,\omega)$ is in agreement with the Hugenholtz-van
Hove (Luttinger-Ward) theorem $\mu-\mu_0= \Sigma(k_{\rm F},\mu)$ and which is
not. The correlation part of the lhs h as the RPA asymptotics $a\ln r_s
+a'+O(r_s)$ [in atomic units]. The use of renormalized RPA diagrams for the rhs
yields the similar expression $a\ln r_s+a''+O(r_s)$ with the sum rule $a'= a''$
resulting from three sum rules for the components of $a'$ and $a''$. This
includes in the second order of exchange the sum rule $\mu_{2{\rm
x}}=\Sigma_{2{\rm x}}$ [P. Ziesche, Ann. Phys. (Leipzig), 2006].Comment: 19 pages, 10 figure
Dynamical T-matrix theory for high-density excitons in coupled quantum
  wells

Excitons in coupled quantum wells open the possibility to reach high
densities close to equilibrium. In a recent experiment employing a lateral trap
potential, a blue shift and a broadening of the exciton emission line has been
seen (Snoke, SSC 134). The standard Hartree-Fock treatment can explain the blue
shift but fails to give a finite broadening. Starting from the (spin-dependent)
many-exciton Hamiltonian with direct and exchange potential, we present a
dynamical T-matrix calculation for the single-exciton Green's function which is
directly related to the frequency- and angle-resolved photoluminescence. The
calculated spectrum is blue shifted and broadened due to exciton-exciton
scattering. At high excitation, both the spectrum and the angular emission are
getting narrow. This is a direct manifestation for off-diagonal long range
order and a precursor of condensation.Comment: 7 pages, 3 figures. Proceedings NOEKS 8 (Muenster 2006
Comparative structural-vibrational study of nano-urchin and nanorods of vanadium oxide

We present a comparative structural–vibrational study of nanostructured systems of V2O5: nano-urchin (VONURs) which are spherical structures composed of a radially oriented array of VOx nanotubes (VOx-NTs) with a volumetric density of ∼40 sr–1, and vanadium oxide nanorods (VOx-NRDs) with an average length of ∼100 nm. The Raman scattering spectrum of the nano-urchin exhibits a band at 1014 cm–1 related to the distorted gamma conformation of the vanadium pentoxide (γ-V5+). The infrared vibrational spectra of the nanorods sample also exhibit a distorted laminar V2O5 structure with evidence observed for quadravalent V4+ species at 921 cm–1
Encapsulating C59N azafullerene derivatives inside single-wall carbon
  nanotubes

Filling of single-wall carbon nanotubes with C59N azafullerene derivatives is
reported from toluene solvent at ambient temperature. The filling is
characterized by high resolution transmission electron microscopy and Raman
spectroscopy. The filling efficiency is the same as for C60 fullerenes and the
tube-azafullerene interaction is similar to the tube-C60 interaction. Vacuum
annealing of the encapsulated azafullerene results in the growth of inner
tubes, however no spectroscopic signature of nitrogen built in the inner walls
is detected.Comment: To appear in Carbo
High fidelity measurement of singlet-triplet states in a quantum dot

We demonstrate experimentally a read-out method that distinguishes between
two-electron spin states in a quantum dot. This scheme combines the advantages
of the two existing mechanisms for spin-to-charge conversion with single-shot
charge detection: a large difference in energy between the two states and a
large difference in tunnel rate between the states and a reservoir. As a
result, a spin measurement fidelity of 97% was achieved, which is much higher
than previously reported fidelities.Comment: 4 pages, 1 figur
Size-dependence of anisotropic exchange interaction in InAs/GaAs quantum
  dots

A comprehensive study of the exchange interaction between charge carriers in
self-organized InAs/GaAs quantum dots is presented. Single quantum-dot
cathodoluminescence spectra of quantum dots of different sizes are analyzed.
Special attention is paid to the energetic structure of the charged excited
exciton (hot trion). A varying degree of intermixing within the hot trion
states leads to varying degrees of polarization of the corresponding emission
lines. The emission characteristics change from circularly polarized for small
quantum dots to elliptically polarized for large quantum dots. The findings are
explained by a change of magnitude of the anisotropic exchange interaction and
compared to the related effect of fine-structure splitting in the neutral
exciton and biexciton emission.Comment: 4 pages, 3 figures, to be published in phys. stat. sol (b),
  proceedings of the QD2006, May 1-5 2006, Chamonix-Mont-Blanc, Franc
Selective lasing in multimode periodic and non-periodic nanopillar
  waveguides

We investigate the lasing action in coupled multi-row nanopillar waveguides
of periodic or fractal structure using the finite difference time domain (FDTD)
method, coupled to the laser rate equations. Such devices exhibit band
splitting with distinct and controllable supermode formation. We demonstrate
that selective lasing into each of the supermodes is possible. The structure
acts as a microlaser with selectable wavelength. Lasing mode selection is
achieved by means of coaxial injection seeding with a Gaussian signal of
appropriate transverse amplitude and phase profiles. Based on this we propose
the concept of switchable lasing as an alternative to conventional laser tuning
by means of external cavity control.Comment: 7 pages, 6 figure
Superconductivity in the two-dimensional Hubbard model?

A refined variational wave function for the two-dimensional repulsive Hubbard
model is studied numerically, with the aim of approaching the difficult
crossover regime of intermediate values of U. The issue of a superconducting
ground state with d-wave symmetry is investigated for an average electron
density n=0.8125 and for U=8t. Due to finite-size effects a clear-cut answer to
this fundamental question has not yet been reached.Comment: 5 pages, 1 figure, Proc. 30th Int. Conf. of Theoretical Physics,
  Ustron, Poland, 2006, to be published in phys. stat. so
Quasiclassical theory of electronic transport in mesoscopic systems:
  Luttinger liquids revisited

The method of the quasiclassical Green's function is used to determine the
equilibrium properties of one-dimensional (1D) interacting Fermi systems, in
particular, the bulk and the local (near a hard wall) density of states. While
this is a novel approach to 1D systems, our findings do agree with standard
results for Luttinger liquids obtained with the bosonization method. Analogies
to the so-called $P(E)$ theory of tunneling through ultrasmall junctions are
pointed out and are exploited. Further applications of the Green's function
method for 1D systems are discussed.Comment: 7 pages, Proceedings of ECNM06, Ustron, Poland (references added