摘要:

The nonlinear micromagnetic equations are used to obtain an approximate analytical solution for the distribution of the magnetization vector in the central plane of a ferromagnetic plate with uniaxial magnetocrystalline anisotropy. It is shown that the micromagnetic nucleation mode derived from the linearized equations develops into a strip domain pattern with well‐defined Bloch walls in a rather narrow range of applied magnetic field near the saturation value. The stability of the domain pattern is discussed qualitatively.

ISSN:0021-8979    

DOI:10.1063/1.1709916

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Single‐crystal foils of the compound Bi2Te3were irradiated with 7.5‐MeV protons at two levels of flux to the same integrated dose of 5.5×1018protons/cm2. The specimens were examined by transmission electron microscopy. After irradiation with a flux of 1.8×1013protons/cm2·sec, clusters of point defects ranging in size from approximately 50 to 250 Å were observed. These clusters annealed out during examination in the electron microscope. After irradiation with a flux of 3.0×1013protons/cm2·sec, clusters of interstitial atoms and clusters of vacancies could be distinguished. Hexagonal areas were observed after irradiation with the higher flux. Irradiation also promoted the rearrangement of dislocations. Segments of dislocations intersected the surface of the specimens, and some dislocations acquired a jagged appearance.

ISSN:0021-8979    

DOI:10.1063/1.1709917

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

It is shown that the anisotropic permeability of the magnetic particles constituting an artificial dielectric provides an explanation for the rotation of the plane of polarization and the variation of the attenuation of a plane‐polarized electromagnetic signal propagating through the dielectric in the presence of a longitudinal magnetic field. The attenuation curve is found to be readily explainable from the nature of variation of the power transmitted into the particles. A more detailed agreement between experimentally observed rotation, attenuation, and computed values is shown to follow if Lewin's formulas for the permeability and permittivity of an artificial dielectric is assumed to be valid also for circularly polarized signals. The effect of the size and permeability of the metal particles on the figure of merit of rotation is also discussed.

ISSN:0021-8979    

DOI:10.1063/1.1709918

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The longitudinal magnetoresistance and Hall mobility of 5‐&OHgr;·cmn‐type germanium have been measured for electric fields applied in the (111) direction up to 4 kV/cm. It has been found that (i) longitudinal magnetoresistance at a particular electric field decreases with an increase in the magnetic field, (ii) for small magnetic fields the longitudinal magnetoresistance decreases with an increase in the electric field, and (iii) the Hall mobility and the ratio of Hall mobility to the conductivity mobility decrease with an increase in the electric field.The experimental value for fields above 1 kV/cm are found to agree with the theoretical values calculated with the assumptions that (i) the scattering is due to the acoustic, optical, and intervalley phonons, (ii) the average energy of the electrons is much larger than that of the optical phonons, (iii) the intervalley phonons affect only the carrier repopulation in the different valleys, and (iv) the value of the optical‐phonon deformation potential constant is 0.8×109eV/cm.

ISSN:0021-8979    

DOI:10.1063/1.1709919

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The phosphor MgS:Ce,Ni is an efficient cathodoluminophor with green to yellow emission and very short decay time. The addition of nickel produces lower efficiency and correspondingly faster decay, the exact relation depending on the cerium concentration. The optimum composition for high efficiency (5–10 lm/W) and fast decay (0.25–0.35 &mgr;sec) was found to be MgS:Ce (0.001), Ni (0.0002). The primary green luminescence was shown to result from cerium doping rather than from some other impurity.

ISSN:0021-8979    

DOI:10.1063/1.1709920

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Soleillet's theory of light scattering by a random aggregation of dipoles has been extended through Mueller matrix algebra to formulate a matrix for light scattering by an array of oriented dipoles. The proposed matrix reveals certain interesting characteristics of dipolar scattering. Linear relations between the parameters of the Stokes' vectors of incident and scattered beams have been obtained for the case of oriented dipoles. The applicability of the matrix has been indicated in the case of radiations in the horizontal plane from an ungrounded antenna or an array of antennas oriented in the vertical plane, and in polarization studies of light scattering by oriented polymer films and fibers which have completely aligned long‐chain molecules.

ISSN:0021-8979    

DOI:10.1063/1.1709921

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The effect of impurities on the annealing behavior of irradiated silicon was studied through an investigation of isothermal annealing of minority carrier lifetime in silicon crystals containing phosphorus, arsenic, antimony, or bismuth in the temperature range 100°–180°C. The activation energy for the annealing of vacancy‐impurity complex increased with increasing atom size of the dopant. The values are 0.93, 1.27, 1.84, and 2.22 eV. The frequency factor was also found to be dependent on impurity as well as concentration of the complex. The variation of these parameters is discussed in terms of the lattice strain associated with impurity atoms which have a larger covalent radius than silicon.

ISSN:0021-8979    

DOI:10.1063/1.1709922

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The variation of contact resistance with temperature has been measured on clean and tarnished silver contacts between 77° and 420°K. It is shown that the temperature coefficient of resistance provides a direct method of distinguishing film conduction from metallic conduction in contacts, and conversely that a single measurement at room temperature cannot reliably yield this information. Clean contacts have the positive temperature coefficient of resistance of the conductor metal. A film‐covered contact on the other hand exhibits either of two distinct types of temperature dependence: one with a large negative temperature coefficient, and one that is metallic. It is suggested that these occur according to whether mechanical contact is made on the film or through a small fissure in it. If the contact is mechanically disturbed, the nature of the conduction fluctuates randomly between these two modes.Further, the temperature coefficient of resistance provides a means for distinguishing between semiconducting and tunneling contacts. The experimental observations on silver sulfide tarnish film suggest that electron tunneling is dominant at cryogenic temperatures, but that at normal temperatures the film is ann‐type semiconductor.

ISSN:0021-8979    

DOI:10.1063/1.1709923

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The electron scattering at the surfaces of an Au film vacuum deposited on Bi2O3is analyzed as a function of film thickness using the Fuchs‐Sondheimer theory modified to allow the determination of the scattering parameters separately at each of the film surfaces. The scattering at the air‐Au interface becomes less specular as Au‐film thickness increases. In the analysis the assumption is made that the scattering parameter at the Au−Bi2O3interface is unaffected by variation in Au‐film thickness. The justification for this assumption is the strong influence of the Bi2O3on the growth characteristic of the Au film. It is known that a given Au‐film thickness will become continuous when deposited on Bi2O3, whereas a film of that same thickness would be discontinuous deposited on bare glass or quartz.

ISSN:0021-8979    

DOI:10.1063/1.1709924

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Fe‐Co and Fe‐V alloys, tested in static ultrahigh pressure apparatus, have been found to have resistance jumps resulting from the &agr; to &egr; transformation, as in pure Fe. The pressure of initiation of the transformation increases with the alloy content; from 131 kbar for pure Fe up to 290 kbar for 20 wt% Co. The V alloys rise much faster: 280 kbar at 6 wt%. The Fe‐Co alloys can serve as convenient samples to pressure‐calibrate apparatus in the 160 to 300‐kbar region. The difference between the pressures of initiation of transformation under static conditions, compared to shock conditions, is zero for pure Fe and progressively greater as the alloy content increases.

ISSN:0021-8979    

DOI:10.1063/1.1709925

出版商:AIP    

年代:1967

数据来源: AIP