Frequency dispersion of the magnetic anisotropy field in metallic magnetic films with the plane anisotropy of electrical conductivity

Presence of the frequency dispersion of the field of induced single axis magnetic anisotropy and the angular position of the axis of easy magnetization in the film plane has been determined in metallic magnetic films with plane anisotropy of electrical conductivity. Theoretical dependences have been obtained which given satisfactory agreement with experimental data for cobalt and permalloy films prepared by sputtering on glass substrates and using the incident molecular beam under an angle with the substrate.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 76–78, January, 1986.In conclusion, we thank D. I. Sementosva for a useful critique during the discussion of the subject-matter of the present work.     

Interaction of optical phonons with magnons in orthorhombic crystals and the effect of magnetic field on structural phase transitions

The interaction of polar optical phonons with magnons in RMn₂O₅ manganates (R is a rare earth ion) has been studied in the approximation of collinear antiferromagnetic ordering of manganese sublattices. The effect of magnetic field on the structural phase transitions in these oxides has been analyzed.     

Influence of magnetic field on acoustic emission in dislocation-containing silicon under current loading

The influence of weak (<1 T) magnetic fields on acoustic emission (AE) of dislocation-containing n-Si(111) under current loading j=(1?5)×10⁵ A/m² is investigated. It is found that the combined effect of the magnetic and electric fields leads to an increase in the acoustic emission response by a factor of 1.5 and is responsible for the emergence of an additional peak in the AE spectra at a frequency of 1.7–1.8 Hz. The result is explained by the influence of magnetic fields, which changes the energy state of paramagnetic stoppers. This facilitates the separation and motion of dislocations. Withdrawal of the magnetic field leads to the relaxation of acoustic emission processes, which is determined by the dynamics of excited point centers interacting with a dislocation.     

磁场对La2－xSrxCuO4单晶热导的影响研究

报道了系列欠掺杂La_2-xSr_xCuO₄（x=0063,0070,0 090,0110,0125）单晶的零场和加磁场情况下ab面和c方向的热导率与温度的关系曲线，测量 温度范围从2到45K. 研究发现ab面和c方向的热导率都受到磁场的压制. 而且在磁场 的作用下，热导压制率随温度变化的关系和场致反铁磁有序的增强与温度的依赖关系有高度 相似性. 认为磁场引起的ab面的热导压制主要是电子热导的变化所致，而c方向的 压制则可能主要来源于声子热导的变化，它们均可能与磁场诱导下欠掺杂La_2-x Sr_xCuO₄的某种电荷有序和磁有序的增强密切相关. 关键词： 热导 电荷有序 磁有序     

Influence of a weak magnetic field on microplasticity of silicon crystals

The possibility of magnetic ordering at dangling bonds in dislocation cores has been investigated theoretically. It has been experimentally shown that magnetic ordering in dislocations affects the spin-dependent effects occurring in dislocation crystals of silicon. It has been found that preliminary magnetic treatment of silicon crystals in a weak magnetic field leads to the suppression of the electroplastic effect induced in silicon crystals excited by an electric current. It has been assumed that a change in the microplasticity under the combined action of a magnetic field and an electric current is caused by a weakening of spin-dependent recombination at dislocation dangling bonds.     

Influence of the degree of disorder of amorphous solids on the intensity of light scattering by acoustic phonons

It is observed experimentally that in the low-frequency Raman light scattering spectrum of amorphous porous silicon the boson peak situated in the acoustic range is more sensitive to the structural order than the optical mode presently used to determine the degree of disorder. It is shown that this is because, unlike the coefficient of interaction with optical vibrations, the coefficient of interaction between light and acoustic vibrations contains an additional factor, the square of the reciprocal correlation length of the vibrational excitations, i.e., the intensity of light scattering by acoustic phonons has an additional dependence on the degree of disorder. Zh. éksp. Teor. Fiz. 114, 315–321 (July 1998)     

Influence of the current density longitudinal distribution in current sheets on their magnetic field structure and formation dynamics. I: Calculation of the magnetic field of current sheets with different configurations

The structure of the current sheet magnetic fields are numerically calculated for different distributions of the current density across the current sheet width. The structural features of the magnetic fields of current sheets with current density double-humped distributions are revealed.     

An introduced effective-field theory study of spin-1 transverse Ising model with crystal field anisotropy in a longitudinal magnetic field

A spin-1 transverse Ising model with longitudinal crystal field in a longitudinal magnetic field is examined by introducing an effective field approximation (IEFT) which includes the correlations between different spins that emerge when expanding the identities. The effects of the crystal field as well as the transverse and longitudinal magnetic fields on the thermal and magnetic properties of the spin system are discussed in detail. The order parameters, Helmholtz free energy, entropy and specific heat curves are calculated numerically as functions of the temperature and Hamiltonian parameters. A number of interesting phenomena such as reentrant phenomena originating from the temperature, crystal field, transverse and longitudinal magnetic fields have been found.     

Influence of alloy composition on the dependence of the diffusivity-mobility ratio in ternary semiconductors on a quantizing magnetic field

An expression is derived for the diffusivity-mobility ratio in degenerate narrow-gap ternary semiconductors in the presence of a quantizing magnetic field. With the help of this expression, the diffusivity-mobility ratio is shown, taking n-Hg_1–xCd_xTe as an example, to have an oscillatory dependence on a quantizing magnetic field. The influence of alloy composition on such dependence is also investigated.     

The influence of a weak magnetic field on the radiation-induced conductivity of C60 single crystals

The radiation-induced conductivity of C₆₀ single crystals is found to increase under the influence of a weak magnetic field (B < 1 T). It is shown that the observed effect is not related to the known galvanomagnetic phenomena. The results obtained are explained in terms of the proposed mechanisms of the influence of a weak magnetic field on the spin-dependent processes involving intermediate electron-hole pairs generated under radiation excitation of the fullerite single crystals.     

Influence of external magnetic field on dust acoustic waves in a capacitive RF discharge

This paper reports experiments on self-excited dust acoustic waves (DAWs) and its propagation characteristics in a magnetized rf discharge plasma. The DAWs are spontaneously excited in dusty plasma after adding more particles in the confining potential well and found to propagate in the direction of streaming ions. The spontaneous excitation of such low-frequency modes is possible due to the instabilities associated with streaming ions through the dust grain medium. The background E-field and neutral pressure determine the stability of excited DAWs. The characteristics of DAWs strongly depend on the strength of external magnetic field. The magnetic field of strength B < 0.05 T only modifies the characteristics of propagating waves in dusty plasma at moderate power and pressure, P = 3.5 W and p = 27 Pa, respectively. It is found that DAWs start to be damped with increasing the magnetic field beyond B > 0.05 T and get completely damped at higher magnetic field B ∼ 0.13 T. After lowering the power and pressure to 3 W and 23 Pa respectively, the excited DAWs in the absence of B are slightly unstable. In this case, the magnetic field only stabilizes and modifies the propagation characteristics of DAWs while the strength of B is increased up to 0.1 T or even higher. The modification of the sheath electric field where particles are confined in the presence of the external magnetic field is the main cause of the modification and damping of the DAWs in a magnetized rf discharge plasma.     

Roles of the magnetic field and electric current in thermally activated domain wall motion in a submicrometer magnetic strip with perpendicular magnetic anisotropy

We have experimentally studied micrometer-scale domain wall (DW) motion driven by a magnetic field and an electric current in a Co/Pt multilayer strip with perpendicular magnetic anisotropy. The thermal activation energy for DW motion, along with its scaling with the driving field and current, has been extracted directly from the temperature dependence of the DW velocity. The injection of DC current resulted in an enhancement of the DW velocity independent of the current polarity, but produced no measurable change in the activation energy barrier. Through this analysis, the observed current-induced DW velocity enhancement can be entirely and unambiguously attributed to Joule heating.     

Influence of the intrinsic magnetic moment of an electron on the filling of energy levels of a nonrelativistic degenerate electron gas in a quantizing magnetic field

The effect of a quantizing magnetic field on the filling of energy subbands of a degenerate nonrelativistic electron gas, whose magnetic moments are parallel and antiparallel to the direction of the field, is studied. Calculations are made under the assumption that the Fermi kinetic energy of the electron system increases as a result of Pauli's paramagnetism as compared to the kinetic energy calculated without taking this effect into account. Numerical values of the electron concentration are calculated as a function of the magnetic moment direction for magnetic fields under which the electrons are in states with given numbers of the Landau quantum level.A. S. Pushkin State Education Institute, Brest. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 9–13, June, 1992.     

Dependence of the electric conductivity of a thin cylindrical wire in a longitudinal magnetic field on the character of electron reflection

The electric conductivity of a cylindrical metal wire in a longitudinal magnetic field is analyzed with regard to the specular-diffuse boundary condition for electrons. Based on the analytic solution obtained, a theoretical interpretation is given to the experimental data on the magnetoresistance of a thin cylindrical wire. An efficient method for determining the specular reflection coefficient of metal surfaces is proposed.     

Influence of the current density longitudinal distribution in current sheets on their magnetic field structure and formation dynamics. II: Formation dynamics of variously configured current sheets

The structure of Ampere forces responsible for the formation dynamics of classical and double-humped current sheets in magnetic fields with a null line is calculated numerically. Calculation data are compared with experimental data for the structure and dynamics of current sheets obtained using magnetic measurements and holographic interferometry.