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1.
R. Rajaraman 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):157-162
We present here an elementary pedagogical introduction to CPN solitons in quantum Hall systems. We begin with a brief introduction to both CPN models and to quantum Hall (QH) physics. We then focus on spin and layer-spin degrees of freedom in QH systems and point
out that these are in fact CPN fields for N
= 1 and N
= 3. Excitations in these degrees of freedom will be shown to be topologically non-trivial soliton solutions of the corresponding
CPN field equations. We conclude with a brief summary of our own recent work in this area, done with Sankalpa Ghosh.
Received 17 November 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: doug0700@mail.jnu.ac.in 相似文献
2.
V.S. Gerdjikov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):237-241
We compare the Hamiltonian properties of the N-soliton solutions of the NLSE in the adiabatic approximation and show how it matches the Hamiltonian formulation for the
complex Toda chain which describes the adiabatic N-soliton interactions.
Received 21 October 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
3.
4.
G.-P. Zhang S.-J. Xiong 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(3):491-495
We show that the electronic states in a one-dimensional (1D) Anderson model of diagonal disorder with long-range correlation
proposed by de Moura and Lyra exhibit localization-delocalization phase transition in varying the energy of electrons. Using
transfer matrix method, we calculate the average resistivity and investigate how it changes with the size of the system N. For given value of α (> 2) we find critical energies Ec1 and Ec2 such that the resistivity decreases with N as a power law ∝ N
- γ for electron energies within the range of [E
c1, E
c2], and exponentially grows with N outside this range. Such behaviors persist in approaching the transition points and the exponent γ is in the range from 0.92
to 0.96. The origin of the delocalization in this 1D model is discussed.
Received 18 December 2001 / Received in final form 2 May 2002 Published online 14 October 2002
RID="a"
ID="a"e-mail: sjxiong@nju.edu.cn 相似文献
5.
V.S. Gerdjikov G.G. Grahovski N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):243-248
The class of nonlinear evolution equations (NLEE) - gauge equivalent to the N-wave equations related to the simple Lie algebra are derived and analyzed. They are written in terms of (x, t) ∈ satisfying r = rank nonlinear constraints. The corresponding Lax pairs and the time evolution of the scattering data are found. The Zakharov-Shabat
dressing method is appropriately modified to construct their soliton solutions.
Received 20 October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
6.
E. Nissimov S. Pacheva 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):197-201
The recently proposed supersymmetric extensions of reduced Kadomtsev-Petviashvili (KP) integrable hierarchies in N = 1, 2 superspace are shown to contain in the purely bosonic limit new types of ordinary non-supersymmetric integrable systems.
The latter are coupled systems of several multi-component non-linear Schr?dinger-like hierarchies whose basic nonlinear evolution
equations contain additional quintic and higher-derivative nonlinear terms. Also, we obtain the N = 2 supersymmetric extension of Toda chain model as Darboux-B?cklund orbit of the simplest reduced N = 2 super-KP hierarchy and find its explicit solution.
Received 13 September 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: nissimov@inrne.bas.bg
RID="b"
ID="b"e-mail: svetlana@inrne.bas.bg 相似文献
7.
V.S. Gerdjikov A. Kyuldjiev G. Marmo G. Vilasi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):177-181
We consider generalizations of the standard Hamiltonian dynamics to complex dynamical variables and introduce the notions
of real Hamiltonian form in analogy with the notion of real forms for a simple Lie algebra. Thus to each real Hamiltonian
system we are able to relate several nonequivalent ones. On the example of the complex Toda chain we demonstrate how starting
from a known integrable Hamiltonian system (e.g. the Toda chain) one can complexify it and then project onto different real forms.
Received 18 October 2001 / Received in final form 24 May 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
8.
A. Urbina C. Díaz-Paniagua A.F. Braña F. Batallán 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(4):463-468
We present measurements of the diagonal Rxx and off-diagonal Rxy magnetoresistance under quantum Hall conditions on several high electron mobility transistors (HEMT) based on InxGa1-xAs quantum wells. From the magnetoresistance tensor we obtain the longitudinal conductivity σ
xx
. We study the transport mechanisms near the σ
xx
minima at temperatures ranging between 2 K and 35 K; activated transport is the dominant mechanism for temperatures above
7 K while variable range hopping conductivity is significant for lower temperatures. We show that electron-electron correlations
should be taken into account to explain the conductivity vs temperature behaviour below 5 K. Finally, we study the behaviour of the localization length as a function of Landau level
filling and obtain a critical exponent γ = 3.45±0.15.
Received 6 June 2001 and Received in final form 16 October 2001 相似文献
9.
M.N. Kiselev H. Feldmann R. Oppermann 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(1):53-63
We represent the generators of the SU(N) algebra as bilinear combinations of Fermi operators with imaginary chemical potential. The distribution function, consisting
of a minimal set of discrete imaginary chemical potentials, is introduced to satisfy the local constraints. This representation
leads to the conventional temperature diagram technique with standard Feynman codex, except that the Matsubara frequencies
are determined by neither integer nor half-integer numbers. The real-time Schwinger-Keldysh formalism is formulated in the
framework of complex equilibrium distribution functions for auxiliary semi-fermionic fields. We discuss the continuous large
N and SU(2) large spin limits. We illustrate the application of this technique for magnetic and spin-liquid states of the Heisenberg
model.
Received 26 February 2001 and Received in final form 25 April 2001 相似文献
10.
W. Kockelmann M. Hofmann O. Moze S.J. Kennedy K.H.J. Buschow 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):25-32
The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R
=
Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize
in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively,
corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T
N
= 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R
=
Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively.
Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002 相似文献
11.
P. Mierzyński K. Pomorski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):311-314
Strutinsky shell corrections for the cesium-coated fullerenes were investigated. The single particle levels of electrons are
obtained using the spherical mean-field potential of a shifted Wood-Saxon type. The parameters of the potential are adjusted
to reproduce the experimental ionization energies of the Cs(N) clusters and the magic numbers observed in their photo-ionization spectra of the C60Cs(N) aggregates.
Received 24 May 2002 / Received in final form 9 July 2002 Published online 15 October 2002
RID="*"
ID="*"This work has been partly supported by the Polish Committee for Scientific Research under Contract No. 2P03B 115 19
and by the Program of Scientific Exchange between the IN2P3-France and the Polish Research Institution No. 99-95.
RID="b"
ID="b"e-mail: Krzysztof.Pomorski@umcs.lublin.pl 相似文献
12.
D. Schwarzhans D. Zimmermann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(2):193-198
The absorption spectrum of NaAr has been investigated with high resolution using a supersonic beam of molecules and a tunable
dye laser. About 3 300 absorption lines due to the transition A
2
Π ←
X and B
2
Σ ←
X have been observed. In addition, we observed the spectral distribution of the fluorescence for a particular absorption line.
From all experimental data the X
2
Σ
+
interaction potential has been deduced in a fully quantum-mechanical method of approach. The potential is given in terms
of an analytical Hartree-Fock-Dispersion function. For the equilibrium parameters of the X state we get R
e
= 5.01(1) ? and D
e
= 41.6(2)
cm
-1
.
Received 28 August 2002 / Received in final form 15 October 2002 Published online 17 December 2002
RID="a"
ID="a"Now at Knick Elektronische Messger?te, Beuckestr. 22, 14163 Berlin, Germany.
RID="b"
ID="b"e-mail: dz@kalium.physik.tu-berlin.de 相似文献
13.
M. Jourdan N. Blümer H. Adrian 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):25-30
Superconducting SrTiO
3 - δ
was obtained by annealing single crystalline SrTiO3 samples in ultra high vacuum. An analysis of the V
(
I
) characteristics revealed very small critical currents I
c
which can be traced back to an unavoidable doping inhomogeneity. R
(
T
) curves were measured for a range of magnetic fields B at I
≪
I
c
, thereby probing only the sample regions with the highest doping level. The resulting curves B
c2
(
T
) show upward curvature, both at small and strong doping. These results are discussed in the context of bipolaronic and conventional
superconductivity with Fermi surface anisotropy. We conclude that the special superconducting properties of SrTiO
3 - δ
can be related to its Fermi surface and compare this finding with properties of the recently discovered superconductor MgB2.
Received 4 December 2002 / Received in final form 10 March 2003 Published online 23 May 2003
RID="a"
ID="a"e-mail: jourdan@uni-mainz.de 相似文献
14.
E. García-Matres J.L Martínez J. Rodríguez-Carvajal 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(1):59-70
A neutron diffraction study, as a function of temperature, of the title compounds is presented. The whole family (space group
Immm, a
≈ 3.8?, b
≈ 5.8?, c
≈ 11.3?) is structurally characterised by the presence of flattened NiO6 octahedra that form chains along the a-axis, giving rise to a strong Ni-O-Ni antiferromagnetic interaction. Whereas for Y-compound only strong 1D correlations exist
above 1.5 K, presenting the Haldane gap characteristic of 1D AF chain with integer spin, 3D AF ordering is established simultaneously
for both R and Ni sublattices at temperatures depending on the rare earth size and magnetic moment. The magnetic structures
of R2BaNiO5 ( R
=
Nd, Tb, Dy, Ho, Er and Tm) have been determined and refined as a function of temperature. The whole family orders with a magnetic
structure characterised by the temperature-independent propagation vector
= (1/2, 0, 1/2). At 1.5 K the directions of the magnetic moments differ because of the different anisotropy of the rare earth ions. Except
for Tm and Yb (which does not order above 1.5 K), the magnetic moment of the R3+ cations are close to the free-ion value. The magnetic moment of Ni2+ is around 1.4
, the strong reduction with respect to the free-ion value is probably due to a combination of low-dimensional quantum effects
and covalency. The thermal evolution of the magnetic structures from T
N
down to 1.5 K is studied in detail. A smooth re-orientation, governed by the magnetic anisotropy of R3+, seems to occur below and very close to T
N
in some of these compounds: the Ni moment rotates from nearly parallel to the a-axis toward the c-axis following the R moments. We demonstrate that for setting up the 3D magnetic ordering the R-R exchange interactions cannot
be neglected.
Received 19 July 2001 相似文献
15.
S. Murugesh Radha Balakrishnan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):193-196
We apply our recent formalism establishing new connections between the geometry of moving space curves and soliton equations,
to the nonlinear Schr?dinger equation (NLS). We show that any given solution of the NLS gets associated with three distinct
space curve evolutions. The tangent vector of the first of these curves, the binormal vector of the second and the normal
vector of the third, are shown to satisfy the integrable Landau-Lifshitz (LL) equation = ×, ( = 1). These connections enable us to find the three surfaces swept out by the moving curves associated with the NLS. As an
example, surfaces corresponding to a stationary envelope soliton solution of the NLS are obtained.
Received 5 December 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: radha@imsc.ernet.in 相似文献
16.
B. Gorshunov P. Haas M. Dressel V.I. Torgashev V.B. Shirokov A.V. Prokofiev W. Assmus 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(4):427-435
The infrared spectra of the one-dimensional antiferromagnet LiCuVO4 are measured in the frequency range from 10 cm-1 to 10 000 cm-1 and at temperatures from 2 K to 300 K, for the electric field vector E of the radiation polarized either along the a- or along the b-crystallographic directions. For each polarization six infrared active phonon modes are observed in accordance with factor
group analysis of the crystal structure of LiCuVO4. The theoretical group analysis of the possible spinel low-symmetry phases is performed within the framework of Landau's
theory of phase transitions. The parameters of several phonon lines show noticeable anomalies around 150 K where the magnetic
correlations appear in the copper chains, which may indicate a finite interaction between the phonon and the magnon subsystems
in LiCuVO4.
Received 19 February 2001 and Received in final form 26 June 2001 相似文献
17.
N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):255-259
We consider quasi-periodic and periodic (cnoidal) wave solutions of a set of n-component dynamical systems related to Korteweg-de Vries equation. Quasi-periodic wave solutions for these systems are expressed
in terms of Novikov polynomials. Periodic solutions in terms of Hermite polynomials and generalized Hermite polynomials for
dynamical systems related to Korteweg-de Vries equation are found.
Received 15 October 2001 / Received in final form 6 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: nakostov@ie.bas.bg 相似文献
18.
T. Dobrowolski 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):269-271
The production of topological defects during a quench in a φ4 model is investigated. The influence of a spatially correlated noise on defect production in two and three dimensions is
demonstrated.
Received 28 August 2001 / Received in final form 11 February 2002 Published online 2 October 2002
RID="a"
ID="a"Paper supported in part by ESF “COSLAB” Programme
RID="b"
ID="b"e-mail: sfdobrow@kinga.cyf-kr.edu.pl 相似文献
19.
A.E. Robson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):117-118
Eur. Phys. J. D 15, 87 (2001)
Received 12 January 2001 Published online 10 December 2002
RID="a"
ID="a"e-mail: aerobson@cstone.net 相似文献
20.
F.S. da Rocha G.L.F. Fraga D.E. Brand?o C.M. Granada C.M. da Silva A.A. Gomes 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):307-311
The magnetic moment of the Mn impurities was obtained from magnetization measurements of Y
(
Ni
1 - x
Mn
x
)
2
B
2
C as a function of the concentration x less than 0.15. Using the coherent potential approximation and starting from 3
d density of states, obtained from the first principles calculations, the magnetic moments are obtained within a two sublattice
model. For adequately estimated values of the Coulomb interactions U, the position of the energy level of Mn and adopting values for the intersublattice hybridization term, a qualitative agreement
with the observed experimental data is obtained.
Received 23 April 2001 and Received in final form 29 October 2001 相似文献