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1.
Possible effects of strong local anisotropy in the vicinity of a μ meson occupying a rare-earth metal interstitial site are considered. The distortion of the magnetic structure and the corresponding
contribution to the dipolar field at the muon are calculated. A threshold-type change of the dipolar field depending on the
local anisotropy or external magnetic field is predicted for the case where the direction toward the muon is perpendicular
to the magnetic moment of one in the ions. The possibility of existence of two strengths of the dipolar field for the ferromagnetic
phases of Dy and Tb, and of its abrupt change depending on the direction of the magnetic moment of the plane is predicted
for helical antiferromagnetic structures.
Fiz. Tverd. Tela (St. Petersburg) 40, 1298–1304 (July 1998) 相似文献
2.
We study the magnetic states and phase transitions in layered triangular antiferromagnets and show that in compounds of the
VBr2 (or VCl2) type the quantum effects alter the structure of the ground state and initiate a series of transitions as the magnetic field
strength is increased. We establish that planar structures with different spin configurations are realized when the magnetic
field strength is far from the saturation value, while a nonplanar structure of the umbrella type is realized in fields close
to the saturation value. Finally, we build the phase diagram of the ground state and indicate a finite range of field strengths
where a collinear phase is possible, too.
Zh. éksp. Teor. Fiz. 111, 627–643 (February 1997) 相似文献
3.
Zurab Berezhiani 《The European Physical Journal C - Particles and Fields》2009,64(3):421-431
It was pointed out recently that oscillation of the neutron n into a mirror neutron n′, a sterile twin of the neutron with exactly the same mass, could be a very fast process with baryon number violation, even
faster than the neutron decay itself. This process is sensitive to magnetic fields and it could be observed by comparing the
neutron loss rates in the UCN storage chambers for different magnetic backgrounds. We calculate the probability of the n−n′ oscillation in the case when a mirror magnetic field B′ is non-zero and show that in this case it can be suppressed or resonantly enhanced by applying the ordinary magnetic field B, depending on its strength and on its orientation with respect to B′. The recent experimental data, under this hypothesis, still allow for an n−n′ oscillation time of order 1 s or even smaller. Moreover, they indicate that the neutron losses are sensitive to the orientation
of the magnetic field. If these hints will be confirmed in future experiments, this would point to the presence of a mirror
magnetic field on the Earth of the order of 0.1 G, or some equivalent spin-dependent force of other origin that makes a difference
between the neutron and mirror neutron states. 相似文献
4.
K. G. Kostov M. A. Algatti E. J.D.M. Pillaca M. E. Kayama R. P. Mota R. Y. Honda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):205-209
In this work we describe a two-dimensional computer simulation of magnetic field enhanced plasma immersion implantation system.
Negative bias voltage of 10.0 kV is applied to a cylindrical target located on the axis of a grounded vacuum chamber filled
with uniform nitrogen plasma. A pair of external coils creates a static magnetic field with main vector component along the
axial direction. Thus, a system of crossed E×B field is generated inside the vessel forcing plasma electrons to rotate in azimuthal direction. In addition, the axial variation
of the magnetic field intensity produces magnetic mirror effect that enables axial particle confinement. It is found that
high-density plasma regions are formed around the target due to intense background gas ionization by the trapped electrons.
Effect of the magnetic field on the sheath dynamics and the implantation current density of the PIII system is investigated.
By changing the magnetic field axial profile (varying coils separation) an enhancement of about 30% of the retained dose can
be achieved. The results of the simulation show that the magnetic mirror configuration brings additional benefits to the PIII
process, permitting more precise control of the implanted dose. 相似文献
5.
A. A. Bukharaev D. V. Ovchinnikov N. I. Nurgazizov E. F. Kukovitskii M. Klaiber R. Wiesendanger 《Physics of the Solid State》1998,40(7):1163-1168
Isolated Ni nanoparticles were studied in situ by atomic and magnetic force microscopy in the presence of an additional external field up to 300 Oe. By comparing topographic
and magnetic images, and also by computer modeling of magnetic images, it was established that particles smaller than 100
nm are single-domain and easily undergo magnetic reversal in the direction of the applied external magnetic field. For large
magnetic particles, the external magnetic field enhances the magnetization uniformity and the direction of total magnetization
of these particles is determined by their shape anisotropy. Characteristics of the magnetic images and magnetic reversal of
particles larger than 150 nm are attributed to the formation of a vortex magnetization structure in these particles.
Fiz. Tverd. Tela (St. Petersburg) 40, 1277–1283 (July 1998) 相似文献
6.
L. M. Gorbunov R. R. Ramazashvili 《Journal of Experimental and Theoretical Physics》1998,87(3):461-467
We study the generation of a quasistatic magnetic field by a short, circularly polarized laser pulse in a tenuous cold uniform
plasma. It is shown that two physical mechanisms are responsible for the generation of the various components of the magnetic
field. One mechanism is due to the ponderomotive forces and governs the generation of the azimuthal component of the magnetic
field. The other is similar to the inverse Faraday effect (IFE) in a nonuniform plasma and gives rise to axial and radial
components of the magnetic field. At moderate radiative intensities, all magnetic field components are proportional to the
squared intensity. The spatial structure of the magnetic field depends strongly on the pulse shape and the plasma density.
Zh. éksp. Teor. Fiz. 114, 849–863 (September 1998) 相似文献
7.
V. I. Alekseenko 《Technical Physics》1998,43(10):1181-1185
The structural-energy spectrum of the states of a bismuth-containing oxide glass, the sensitivity of these states to the action
of a pulsed magnetic field, and the thermodynamic and kinetic stability of the structure excited by a pulsed magnetic field
are studied by the method of measuring the internal friction. It is established that a pulsed magnetic field influences the
structural states and that this leads to irreversible changes in the structure and the crystallization parameters of the glass.
It is found that the efficacy of acting on a material with a pulsed magnetic field also depends on the parameters of the field
and the structural-energy state of the material and that the action itself is of a thermally-activated relaxational character.
The optimal conditions for the action of a pulsed magnetic field on glass are determined.
Zh. Tekh. Fiz. 68, 50–54 (October 1998) 相似文献
8.
M. N. Khlopkin G. Kh. Panova N. A. Chernoplekov A. A. Shikov A. V. Suetin 《Journal of Experimental and Theoretical Physics》1997,85(4):755-759
The specific heat and resistive upper critical magnetic field of the single crystal La1.85Sr0.15CuO4 are investigated in the temperature range 2–50 K in magnetic fields up to 8 T for two directions of the magnetic field, parallel
and normal to the ab crystalline plane. For both orientations a nonlinear (close to square root) magnetic field dependence of the mixed-state
specific heat and a positive curvature of the temperature dependence of the upper critical magnetic field are observed. Neither
of these anomalies is described by standard theories of superconductivity. Within the framework of the thermodynamic relations
it is shown that in a type-II superconductor a relationship exists between the temperature dependence of the critical magnetic
field and the field dependence of the specific heat. The anomalies observed in these phenomena are interrelated.
Zh. éksp. Teor. Fiz. 112, 1386–1395 (October 1997) 相似文献
9.
The aim of this work is to examine the influence of a weak (on the energy scale) magnetic field on the state of dislocations
and point defects in ionic crystals. It is found that complex point defects existing in a metastable state are sensitive to
a magnetic field B∼1 T. The contributions are identified, and the kinetics of various types of reactions within the structural defects and between
them leading to plastification of the crystals in a magnetic field are determined. The effect of light on the sensitivity
of the point defects to a magnetic field is described, and the spectral characteristics of this effect are determined. A resonant
effect of the combined action of a weak constant magnetic field and a high-frequency magnetic field on the dislocation mobility
is found to occur when these fields satisfy the conditions of electron paramagnetic resonance.
Zh. éksp. Teor. Fiz. 115, 605–623 (February 1999) 相似文献
10.
Yu. F. Filippov 《Technical Physics》1997,42(7):797-802
A rigorous theory of the propagation of electromagnetic waves in round anisotropic and semiconductor rods in the presence
of an arbitrarily directed anisotropy axis or external magnetic field is developed. New types of independent waves are discovered.
Exact dispersion equations are obtained for them, which define the dependence of their spectral characteristics on the parameters
of the semiconductor or anisotropic crystal and on the magnitude and direction of the constant external magnetic field. The
results of numerical investigations for rods made from a semiconductor or a uniaxial crystal are presented.
Zh. Tekh. Fiz. 67, 86–91 (July 1997) 相似文献
11.
Magnetic perturbations in tokamaks lead to the formation of magnetic islands, chaotic field lines, and the destruction of flux surfaces. Controlling or reducing transport along chaotic field lines is a key challenge in magnetically confined fusion plasmas. A local control method was proposed by Chandre et al. [Nucl. Fusion 46, 33–45 (2006)] to build barriers to magnetic field line diffusion by addition of a small second-order control term localized in the phase space to the field line Hamiltonian. Formation and existence of such magnetic barriers in Ohmically heated tokamaks (OHT), ASDEX UG and piecewise analytic DIII-D [Luxon, J.L.; Davis, L.E., Fusion Technol. 8, 441 (1985)] plasma equilibria was predicted by the authors [Ali, H.; Punjabi, A., Plasma Phys. Control. Fusion 49, 1565–1582 (2007)]. Very recently, this prediction for the DIII-D has been corroborated [Volpe, F.A., et al., Nucl. Fusion 52, 054017 (2012)] by field-line tracing calculations, using experimentally constrained Equilibrium Fit (EFIT) [Lao, et al., Nucl. Fusion 25, 1611 (1985)] DIII-D equilibria perturbed to include the vacuum field from the internal coils utilized in the experiments. This second-order approach is applied to the DIII-D tokamak to build noble irrational magnetic barriers inside the chaos created by the locked resonant magnetic perturbations (RMPs) (m, n)=(3, 1)+(4, 1), with m and n the poloidal and toroidal mode numbers of the Fourier expansion of the magnetic perturbation with amplitude δ. A piecewise, analytic, accurate, axisymmetric generating function for the trajectories of magnetic field lines in the DIII-D is constructed in magnetic coordinates from the experimental EFIT Grad-Shafranov solver [Lao, L, et al., Fusion Sci. Technol. 48, 968 (2005)] for the shot 115,467 at 3000 ms in the DIII-D. A symplectic mathematical map is used to integrate field lines in the DIII-D. A numerical algorithm [Ali, H., et al., Radiat. Eff. Def. Solids Inc. Plasma Sc. Plasma Tech. 165, 83 (2010)] based on continued fraction decomposition of the rotational transform labeling the barriers for selecting and identifying the strongest noble irrational barrier is used. The results are compared and contrasted with our previous results on the ASDEX UG. About six times stronger a barrier can be built in the DIII-D than in the ASDEX UG. High magnetic shear near the separatrix in the DIII-D is inferred as the possible cause of this. Implications of this for the DIII-D and the International Thermonuclear Experimental Reactor (ITER) are discussed. 相似文献
12.
Yu. B. Kudasov A. I. Bykov M. I. Dolotenko N. P. Kolokol’chikov M. P. Monakhov I. M. Markevtsev V. V. Platonov V. D. Selemir O. M. Tatsenko A. V. Filippov A. G. Volkov A. A. Povzner P. V. Bayankin V. G. Guk 《JETP Letters》1998,68(4):350-355
The magnetic susceptibility and conductivity of single-crystal iron monosilicide are investigated in ultrahigh magnetic fields
up to 450 T at a temperature of 77 K. It is found that the conductivity of iron monosilicide increases continuously by two
orders of magnitude as the magnetic field increases. The results obtained can be interpreted as a semiconductor-metal transition
induced by the magnetic field. The dependence of the conductivity on the magnetic field is described well on the basis of
the spin-fluctuation theory.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 326–330 (25 August 1998) 相似文献
13.
Various aspects of the influence of an external magnetic field on turbulent flow of a conducting fluid are investigated. The
distributions of electric variables are determined for weak magnetic fields (both the electric field and the current have
nonzero values in this case). For very strong magnetic fields it is shown that turbulent motion acquires a two-dimensional
character. The emergence of an electric current component perpendicular to the flow and to the magnetic field is described
in the case of a temperature-stratified medium in the presence of turbulent heat flux.
Zh. éksp. Teor. Fiz. 111, 528–535 (February 1997) 相似文献
14.
Response of colloidal liquids containing magnetic holes of different volume densities to magnetic field characterized by transmission measurement 下载免费PDF全文
This paper systematically investigates the response of colloidal liquids containing magnetic holes of different volume densities to magnetic field by conventional transmission measurements. It finds that the enhancement in the transmission of such a colloidal liquid under a magnetic field exhibits a strong dependence on the volume density of magnetic holes. A linear increase in the maximum enhancement factor is observed when the volume density of magnetic holes is below a critical level at which a maximum enhancement factor of ~150 is achieved in the near infrared region. Once the volume density of magnetic holes exceeds the critical level, a sharp drop of the maximum enhancement factor to ~2 is observed. After that, the maximum enhancement factor increases gradually till a large volume density of ~9%. By monitoring the arrangement of magnetic holes under a magnetic field, it reveals that the colloidal liquids can be classified into three different phases, i.e., the gas-like, liquid-like and solid-like phases, depending on the volume density of magnetic holes. The response behaviour of colloidal liquids to magnetic field is determined by the interaction between magnetic holes which is governed mainly by their volume density. A phase transition, which is manifested in the dramatic reduction in the maximum enhancement factor, is clearly observed between the liquid-like and solid-like phases. The optical switching operations for colloidal liquids in different phases are compared and the underlying physical mechanisms are discussed. 相似文献
15.
B. S. Dumesh M. I. Kurkin S. V. Petrov A. M. Tikhonov 《Journal of Experimental and Theoretical Physics》1999,88(6):1221-1228
The spectrum and intensities of NMR lines are investigated experimentally and theoretically for excitation by an alternating
magnetic field h‖ parallel to a static field H in the quasi-one-dimensional, six-sublattice antiferromagnet CsMnBr3. According to theory, two new NMR lines, which are not excited by a transverse magnetic field h
⊥, are observed near the phase transition from triangular to collinear structure (H=H
c
) [JETP 86, 197 (1998)].
Zh. éksp. Teor. Fiz. 115, 2228–2241 (June 1999) 相似文献
16.
We have performed measurements of the magnetization and differential magnetic susceptibility of Dy0.62Y2.38Fe5O12 single crystals in pulsed magnetic fields up to 45 T at liquid-helium temperature for three orientations of the external
field: H‖[100], H‖[110], and H‖[111]. It was found that the magnetization reversal in the rare-earth magnetic subsystem occurs via several phase transitions,
whose number depends on the direction of the external field, as is characteristic for Ising magnets. The anomalies in the
field dependences of the magnetization are interpreted on the assumption of quasi-Ising ordering of the rare-earth ions.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 8, 552–556 (25 April 1998) 相似文献
17.
Second harmonic generation by a disordered array of superparamagnetic nanoparticles in a
static magnetic field H is studied experimentally. For H = 0, only hyper-Rayleigh scattering takes place; i.e., the second-harmonic radiation is diffuse and unpolarized. For H ≠ 0, a coherent (specular and linearly polarized) component appears against the hyper-Rayleigh scattering background. The
phase of the coherent component changes by π when the direction of the magnetic field is reversed. It is shown that the effect
can be explained by correlations in the spatial fluctuations of the nonlinear-optical and magnetic polarizabilities of the
particles, taking into account the nonuniformity of the effective (local) static magnetic field. 相似文献
18.
ABSTRACTBy using the variational Monte Carlo (VMC) method, we calculated the 1sσg-state energies, the dissociation energies, and the binding energies of the hydrogen molecule and its molecular ion in the presence of an aligned magnetic field regime between 0 and 10?a.u. The present calculations are based on using two types of compact and accurate trial wave functions, which are put forward for consideration in calculating energies in the absence of a magnetic field. The obtained results are compared with the most recent accurate values. We conclude that the applications of the VMC method can be successfully extended to cover the case of molecules under the effect of a magnetic field. 相似文献
19.
I. I. Chuchaev V. A. Margulis A. V. Shorokhov S. E. Kholodova 《Physics of the Solid State》1999,41(5):774-776
The magnetic response of a two-dimensional layer rolled into a cylinder and located in a longitudinal magnetic field is examined.
The magnetic moment of the degenerate electron gas is studied as a function of the magnetic flux. The shape of the fluctuation
maxima is analyzed in detail. It is shown that at zero temperature there are breaks in each period of the change in the magnetic
moment. Over this period, a plot of the magnetic moment depends strongly on the ratio of the Fermi energy to the size-confinement
energy. In particular, there are no breaks for integral or semi-integral values of the square root of this ratio.
Fiz. Tverd. Tela (St. Petersburg) 41, 856–858 (May 1999) 相似文献
20.
An investigation on the magneto-optic properties of terbium gallium garnet under high magnetic field 下载免费PDF全文
The superexchange interaction on a magnetic ion may be represented by an effective field Hm = $\lambda$M in some paramagnetic materials, here λ is the coefficient of effective field and M = $\chi$He with $\chi$ being the magnetic susceptibility and He being the applied field. The variation of the equivalent $\lambda_{\chi}$with the dynamic applied field is given and the crystal field-splitting levels of the excited configuration 4f75d1 of the Tb3+ ion are calculated in the Tb3Ga5O12. By means of the effective field Hm and the applied field He, the Faraday rotation of Tb3Ga5O12 at 6 K and 41 K, under the high magnetic field and at 0.63 μm wavelength, are presented. Our calculated results are in agreement with the experimental data. 相似文献