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1.
Kazantsev 《Russian Physics Journal》1999,42(10):916-921
Concepts of spherical magnetic multipoles that represent distributions of electric currents over a spherical surface are introduced.
Vector potentials of magnetic multipoles meet solenoidal- and harmonic-field conditions outside of the spherical surface and
are continuous on it. Within the sphere, the vector potential of currents flowing outside of it is represented by the sum
of vector potentials of basis magnetic multipoles with coefficients expressed by spherical multipole moments of system of
currents. This expansion of the vector potential is in many respects analogous to the multipole expansion known from electrostatics.
The first three terms of the expansion represent components of the well-known magnetic moment, the next five terms represent
components of the magnetic quadrupole moment, etc. Possible applications of the magnetic spherical multipole technique are
discussed.
Krasnoyarsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 66–72, October,
1999. 相似文献
2.
Crystal field parameters for ErGaG and Er3+ YAlG and used to compute the temperature dependence of Schottky specific heat, paramagnetic susceptibility, magnetic anisotropy,μ
eff and quadrupole splitting in the range 10–400 K. The hyperfine interaction parametersA andB for166Er and167Er in both the systems are also obtained and in turn used to estimate the nuclear specific heat contribution. The studied
parameters compare well with the available experimental results. 相似文献
3.
We show that nodal points of ground states of some quantum systems with magnetic interactions can be identified in simple
geometric terms. We analyse in detail two different archetypical systems: i) the planar rotor with a non-trivial magnetic
flux Φ and ii) the Hall effect on a torus. In the case of the planar rotor we show that the level repulsion generated by any
reflection invariant potential V is encoded in the nodal structure of the unique vacuum for θ=π. In the second case we prove that the nodes of the first Landau
level for unit magnetic charge appear at the crossing of the two non-contractible circles α−, β− with holonomies h
α-(A)=h
β-(A)=−1 for any reflection invariant potential V. This property illustrates the geometric origin of the quantum translation anomaly.
Received: 6 April 1999 / Accepted: 21 October 2000 相似文献
4.
Starting with partial wave projections of the Compton scattering invariant amplitudes free of kinematical singularities or zeros, generalized electric and magnetic multipole polarizabilities of spin-0 and hadrons are introduced as threshold limits of the non-Born parts of the corresponding electric and magnetic Compton multipoles. These objects, which enter the higher low-energy theorems for elastic γ-hadron scattering, are shown to be acceptable quantum field theoretical generalizations of the usual static multipolar polarizabilities encountered in classical electrodynamics or non-relativistic quantum mechanics. Using the analyticity properties of the amplitudes, sum rules for the generalized electric and magnetic quadrupole polarizabilities of the proton and the pions are written down and evaluated numerically within the two-particle unitarity approximation. 相似文献
5.
In this paper, g
K
-factors of the intrinsic magnetic moments and effective spin gyromagnetic factors (g
seff) of the 167–179Lu isotopes have been studied within the Tamm-Dancoff approximation (TDA) (Kuliev et al, Sov. J. Nucl. Phys.
9, 185 (1969)) by using a realistic potential such as Woods-Saxon potential for the first time. The effects of the spin-spin
and spin-isospin interactions on magnetic moments were investigated. The results of the theoretical calculations are compared
with the experimental data for related nuclei. The experimental values of g
K
and g
seff were computed from the observed magnetic moments (Georg et al, Eur. Phys. J. A3, 225 (1998)) using the spin matrix elements. The theoretical predictions for the g
K
factors exhibit good agreement with the experimental g
K
factors with increasing mass number A of the lutetium isotopes. The strongest influence of the neutron-proton spin interaction occurs at q = −1. Sufficient agreement between the calculated and the experimental values of g
K
is obtained for κ = (45/A) MeV and q = −1. 相似文献
6.
E.E. Vogel 《Journal of Physics and Chemistry of Solids》1974,35(9):1263-1268
The electric multipole interaction (EMI) is studied in general for the case of two rare earth (RE) ions interacting in host crystals possessing C3h symmetry at the ion sites. The particular case of Ce3+ substituted for La3+ in LaCl3 is used as an example. The splitting of two degenerate levels of such a system is studied as an application of elementary group theory, and a notation is proposed for the resulting levels. The angular dependence of the splitting due to the first term of the EMI, namely, the electric quadrupole-quadrupole interaction (EQQ), is obtained for one of the levels of the system under consideration. The ground quartet is studied for the nearest neighbor configuration (nn), and all of the multipoles in the expansion for EMI are kept. The shielding effects, which are very important in this problem, are assumed to depend on one parameter. This makes possible the study of the variation of the splittings with respect to such a parameter. The importance of terms beyond the quadrupole is brought out. 相似文献
7.
Heinz Steudel 《Annalen der Physik》1972,483(1):53-63
As well-known the dynamical interaction theory of molecules or atoms with the electromagnetic field may be based alternatively on one of two HAMILTON ians, IH or IIH. where the vector potential appears in the interaction term of IH while this of IIH is expressed in terms of the electric and the magnetic field strength coupled to atomic multipoles. Using a calculus of transversal functional derivation with respect to a vector function we show that we can go from IH to IIH by a comperatively simple canonical transformation which may be interpreted within the classical theory as well as within as the quantized theory. The equivalence of both HAMILTON ians is lost if, as customary in quantum optics, only a few atomic levels are taken into account. We give a plausible argument that in this case the multipole HAMILTON ian IIH is more suitable. 相似文献
8.
V. I. Vysotskii M. V. Vysotskii 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(2):330-334
Based on the Dirac equation, the features of long-range electromagnetic orientational interaction of slow neutrons with even-even
and even-odd nuclei are considered. This interaction is controlled by a narrow potential barrier arranged beyond the nucleus.
The barrier height is U
tot = 20–40 eV and depends on Z, A, and the nucleus magnetic moment μnucl. The barrier formation is associated with the ponderomotive nonlinear interaction of the anomalous neutron moment with the
nucleus electric field. The barrier transparency for thermal neutrons is D(E) ≈ 0.8–0.95. For cold neutrons, the barrier transparency and their reaction cross sections with nuclei sharply decrease and,
at E → 0, their cross sections tend toward zero. It was shown that the combined effect of the magnetic dipole-dipole and ponderomotive
interaction of the neutron and even-odd nucleus results in the formation of removed symmetrically positioned potential wells
for neutrons beyond the nucleus. The presence of these wells results in the possible existence of short-lived or virtual nucleus-neutron
molecules and the “neutron halo” effect beyond the nucleus. 相似文献
9.
A 3-D Gross-Neveu model with Lorentz-violating term b
μ is studied. The effective potential V
eff with a real or imaginary Lorentz-violating term b
μ is calculated. The gap equation is obtained and the influence of the presence of an additional term b
μ on the symmetry of the theory is examined. 相似文献
10.
G. S. Kupriyanova 《Journal of Applied Spectroscopy》2006,73(1):16-24
Longitudinal relaxation of spin systems (S = 1, 3/2, 3) containing isolated quadrupolar nuclei are studied. The characteristic
features of the relaxation behavior are identified in strong magnetic fields in the presence of chemical shift anisotropy.
Two mechanisms are established that favor involvement of high rank multipoles in the relaxation process: an autocorrelation
mechanism and a cross correlation mechanism. Multipoles of odd rank are involved in the relaxation of nuclei with spin S >
1 as a result of the autocorrelation mechanism (in this case, due to quadrupole interactions). The cross correlation mechanism,
due to correlations between the chemical shift anisotropy and the quadrupole interactions, favors the appearance of multipoles
of even rank. Expressions are presented for the multipole cross relaxation and longitudinal relaxation rates for spin systems
with S = 1, 3/2, 3.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 18–25, January–February, 2006. 相似文献
11.
A. L. Lapolli A. W. Carbonari R. N. Saxena J. Mestnik-Filho 《Hyperfine Interactions》2004,158(1-4):157-161
Perturbed gamma–gamma angular correlation technique was used to measure the hyperfine interactions in the compound GdNiIn
using the 111InCd → and 140La140Ce probe nuclei at the In and Gd sites, respectively. A unique quadrupole frequency with asymmetry parameter η = 0.78 was observed for 111Cd probe at In sites for the measurements above Curie temperature. Below T
C
, the spectra for 111Cd show combined magnetic dipole and electric quadrupole interaction. Below 85 K, a unique magnetic interaction is observed
at 140Ce. A linear relationship between the saturated magnetic hyperfine field and the magnetic transition temperature was observed
for both probes, indicating that the main contribution to the mhf comes from the conduction electron polarization. 相似文献
12.
The constructed thermodynamic theory of magnetic birefringence of transverse sound in easyplane weak ferromagnets with an
axial basal anisotropy induced by boundary conditions has been generalized to the case of additional inclusion of the hexagonal
anisotropy enhanced by isotropic mechanical stresses. The magnetoelastic contribution ΔC
a
to the effective elastic modulus C
44eff = C
44 + ΔC
a
, which determines the phase velocity of the magnetic mode of the acoustic wave in a crystal, has been calculated. It has
been shown that the induced anisotropy with the twofold and sixfold symmetry leads to the appearance of an additional anisotropic
term of the fourfold symmetry in the contribution ΔC
a
. The developed theory has made it possible to satisfactorily describe the existing experiments. 相似文献
13.
J.T. Elizalde Galindo A.H. Adair C.E. Botez V. Corral Flores D. Bueno Baques L. Fuentes Cobas J.A. Matutes-Aquino 《Applied Physics A: Materials Science & Processing》2007,87(4):743-747
Measurements of ac-susceptibility and dc-magnetization were carried out on samples of Ni1-xZnxFe2O4 nanoparticles (x=0, 0.25, 0.5, 0.75) with average diameters 〈D〉≈7 nm. Values of the superparamagnetic blocking temperature
T̄B were obtained from the characteristic temperature behavior of the imaginary susceptibility χimag. An Arrhenius-type law, which accurately describes the relationship between the observation time τobs and the blocking temperature, was used to determine the effective energy barrier to magnetization reversal Ueff. A Zn-content dependence of the energy barrier is observed, where Ueff changes little for 0≤x≤0.25, it peaks at x=0.5, and decreases back upon further Zn-doping. The large increase of Ueff at x=0.5 is attributed to an enhanced magnetic anisotropy induced by the crossover between two spatial arrangements of spins
in the A and B sub-lattices of the ferrimagnetic inverse spinel.
PACS 75.50.Bb; 75.50.Gg; 75.30.Et 相似文献
14.
H. Arenhövel W. Leidemann E.L. Tomusiak 《The European Physical Journal A - Hadrons and Nuclei》2002,14(4):491-509
Formal expressions are derived for the multipole expansion of the structure functions of a general polarization observable
of exclusive electrodisintegration of the deuteron using a longitudinally polarized beam and/or an oriented target. This allows
one to exhibit explicitly the angular dependence of the structure functions by expanding them in terms of the small rotation
matrices d
j
m'm(θ), whose coefficients are given in terms of the electromagnetic multipole matrix elements. Furthermore, explicit expressions
for the coefficients of the angular distributions of the differential cross-section including multipoles up to L
max = 3 are listed in tabular form.
Received: 19 November 2002 / Accepted: 7 May 2002 相似文献
15.
A. Salam 《Molecular physics》2019,117(17):2217-2224
ABSTRACTMolecular QED theory is employed to derive a generalised formula for the dispersion potential between two molecules with mixed electric multipole polarisability tensors of arbitrary order at each centre. This expression is used to readily extract the pair energy shift between an electric dipole polarisable molecule and a mixed electric dipole–octupole polarisable one, and that between two mixed electric dipole–octupole polarisable species. This is done to see whether these interaction energies give rise to higher-order corrections to the Casimir–Polder potential, as was found in the previously calculated case of the dispersion energy shift between an electric dipole polarisable molecule and an electric octupole polarisable one. Interestingly, for orientationally averaged species, both of the computed interaction energies are independent of the octupole weight-3 term, are retarded, and may be interpreted as higher-order corrections in the fine structure constant to the leading dipole–dipole dispersion potential. 相似文献
16.
本文以自制Ge20Sb15Se65硫系玻璃为基质材料,设计一种正八边形结构色散平坦型中红外硫系光子晶体光纤,并采用多极法对其中红外色散和传输特性进行数值研究.结果表明:控制该光纤占空比(d/Λ)在0.323—0.367之间,其色散及传输特性在3—5μm范围内可调.当孔间距Λ=3.4μm,孔直径d=1.1μm时,光纤在4.1—4.9μm波段的色散值在0.8—0.8 ps·nm 1·km 1波动,且具备单模低损耗传输(Loss0.049dB/m),小模场面积(Aeff8.46μm2)特性,适合于中红外非线性应用领域. 相似文献
17.
M. A. Zelikman 《Technical Physics》2009,54(12):1742-1748
The configurations of currents and the profile of a magnetic field penetrating into a finite-length contact at I < I
C
are calculated. The computational method is based on analyzing the continuous variation of the current structure leading
to a decrease in the Gibbs potential. Such an approach makes it possible to find a configuration that sets in when an external
field slightly exceeds H
max and trace the evolution of this configuration with increasing field. It is shown that at H > H
max boundary structures turn into quasi-uniform sequences of vortices the spacing between which oscillates about a mean value
decreasing with increasing H. At some values of H, vortices with a number of fluxoids Φ0 larger by unity start penetrating into the contact in the form of boundary sequences. As the field grows, they produce quasi-uniform
sequences, etc. Vortices with the number of fluxoids Φ0 differing by more than unity can fall into the contact at no field. The penetration of vortices with (k + 1)Φ0 into a contact each cell of which contains kΦ0 is fully identical to the penetration of vortices with one Φ0 into the Meissner configuration. This statement is supported by the almost strict periodicity of mean induction b in the contact versus external field h dependence with a period of 1 along both axes and also by the form of the dependences of the magnetic field in the cells
on the cell-boundary distance. 相似文献
18.
The interaction between particle-like sources of the
nematic director distortions (e.g., colloids, point
defects, macromolecules in nematic emulsions) allows for a useful
analogy with the electrostatic multipole interaction between
charged bodies. In this paper we develop this analogy to the level
corresponding to the charge density and consider the general
status of the pairwise approach to the nematic emulsions with
finite-size colloids. It is shown that the elastic analog of the
surface electric charge density is represented by the two
transverse director components on the surface imposing the
director distortions. The elastic multipoles of a particle are
expressed as integrals over the charge density distribution on
this surface. Because of the difference between the scalar
electrostatics and vector nematostatics, the number of elastic
multipoles of each order is doubled compared to that in the
electrostatics: there are two elastic charges, two vectors of
dipole moments, two quadrupolar tensors, and so on. The
two-component elastic charge is expressed via the vector of
external mechanical torque applied on the particle. As a result,
the elastic Coulomb-like coupling between two particles is found
to be proportional to the scalar product of the two external
torques and does not directly depend on the particles' form and
anchoring. The real-space Green function method is used to develop
the pairwise approach to nematic emulsions and determine its form
and restrictions. The pairwise potentials are obtained in the
familiar form, but, in contrast to the electrostatics, they
describe the interaction between pairs (dyads) of the elastic
multipole moments. The multipole moments are shown to be uniquely
determined by the single-particle director field, unperturbed by
other particles. The pairwise approximation is applicable only in
the leading order in the small ratio particle
size-to-interparticle distance as the next order contains
irreducible three-body terms. 相似文献
19.
R. De Luca A. Fedullo 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(1):59-66
The magnetic states of multi-junction superconducting quantum interference
device containing 2N identical conventional Josephson junctions are studied by
means of a perturbation analysis of the non-linear first-order ordinary
differential equations governing the dynamics of the Josephson junctions in
these devices. In the zero-voltage state, persistent currents are calculated
in terms of the externally applied magnetic flux Φex . The
resulting d.c. susceptibility curves show that paramagnetic and diamagnetic
states are present, depending on the value of Φex . The stability
of these states is qualitatively studied by means of the effective potential
notion for the system. 相似文献
20.
The influence of Coulomb correlations on magnetic and spectral properties in the metallic rutile phase of vanadium dioxide
is studied by state of the art LDA + DMFT method. Calculation results in strongly correlated metallic state with an effective
mass renormalization m*/m ≈ 2. Uniform magnetic susceptibility shows Curie-Weiss temperature dependence with effective magnetic moment, p
efftheor = 1.54μB, in a good agreement with the experimental value p
effexp = 1.53μB that is close to ideal value for V4+ ion with the spin S = 1/2, p
eff = 1.73μB. Calculated spectral function shows well developed Hubbard bands observable in the recent experimental photoemission spectra.
We conclude that VO2 in rutile phase is strongly correlated metal with local magnetic moments formed by vanadium d-electrons. 相似文献