摘要:

It is known that the energy flux of a transient electromagnetic wave can decrease with distance more slowly than the usual inverse‐square law. Such cases are referred to as electromagnetic missiles. The rate of decrease depends on the frequency spectrum of the exciting current. For a class of excitations where the frequency spectrum behaves as ‖&ohgr;‖−1/2−&egr;, the rate of decrease has been stated to bez−2&egr;for 0≤&egr;≤1, implying that &egr; must be less than 1 in order for the decrease to be slower thanz−2. It is shown that, in fact, the case &egr;=1 results in a dependence ofz−2 ln z, i.e., an electromagnetic missile—albeit a weaker one than those previously discussed.

ISSN:0021-8979    

DOI:10.1063/1.347180

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A correlation is observed between the ESR spectra (at 1.12 GHz) and the magnetization inversions of the spin glassAgMn for a Mn concentration of 8.3 at. %. This is because of rearrangement of the spin system during the magnetization inversions. The widths of the ESR linesW↑undW↓which correlate, respectively, with the reversals to positive and negative magnetization are different. This is ascribed to different values of the effective anisotropy constantKduring the two reversals. Thus a relationship is obtained between the ESR linewidth and the anisotropy constant.

ISSN:0021-8979    

DOI:10.1063/1.346692

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Theoretical and experimental results describing the propagation of shear horizontal (SH) surface waves on an isotropic elastic cylinder are presented. Analytical formulas for group velocities are developed. The velocity of impulses of the SH surface waves is determined experimentally. Subsequently, the experimental results are compared to the theoretical values. The measured velocity is close to the group velocity calculated according to our theory for cylinders of finite width. As yet, the existing theories consider only the propagtion of SH surface waves over the unlimited cylinders [I. A. Viktorov, Sov. Phys. Acoust.20, 199 (1974) and L. M. Brekhovski, Sov. Phys. Acoust.13, 541 (1967)].

ISSN:0021-8979    

DOI:10.1063/1.346693

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The relative conversion efficiency of laser energy into x radiation in the range of about 0.8–5.5 keV was investigated as a function of irradiance for planar Cu targets. For two laser pulse durations at two wavelengths—100 ps / 670 ps at a wavelength of 1054 nm and 70 ps/470 ps at 527 nm—the requirements on the laser parameters for good conversion efficiency were established.

ISSN:0021-8979    

DOI:10.1063/1.346694

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The ferromagnetic resonance studies were carried out at room temperature on fine powders of Ho0.85Tb0.15Fe2Hx(x=0–3.1) and Dy0.73Tb0.27Fe2Hx(x=0–3.3) atXandQbands. Thegvalues were found to decrease with increasing hydrogen concentration in both the systems. This data along with the earlier magnetization and Mo¨ssbauer data have been used to explain the observance ofTcompin the hydrogenated samples of Ho0.85Tb0.15Fe2.

ISSN:0021-8979    

DOI:10.1063/1.346695

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new type epitaxial growth was found in lithium phthalocyanine (LiPc) film on KBr(100) prepared by the molecular‐beam epitaxy. The structure was directly observed by transmission electron microscopy and two epitaxial phases were observed. One is bidirectional tetragonal phase KBr(100)(&sqrt;10×&sqrt;10)R±27°−LiPc. The other is a new type of tetradirectional monoclinic phase (&sqrt;10×&sqrt;12.5), in which LiPc lattices match with both K+and Br−ions, which form unusual unit meshes.

ISSN:0021-8979    

DOI:10.1063/1.346696

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Single‐phase Tl2Ca1Ba2Cu2O8thin films with zero‐resistance transition temperature up to 100 K have been prepared on single‐crystal MgO substrates from codeposited Ca‐Ba‐Cu amorphous metallic alloy precursors. After thermal oxidation of the metallic alloy film, Tl from Tl2O3was vapor deposited and diffused into the resulting mixed metal oxide during a rapid high‐temperature anneal. The films prepared in this process are highly oriented with thecaxis normal to the substrate.

ISSN:0021-8979    

DOI:10.1063/1.346697

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Crystallographically textured superconducting YBa2Cu3O7−&dgr;thin films 2–10 &mgr;m in thickness have been grown on (100) MgO substrates by a spray pyrolysis method. The structure, morphology, and composition of the films have been demonstrated by x‐ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy, respectively, to show strong texturing and a composition close to that expected for the bulk ceramic. The onset of the superconducting transition is at 82 K and zero resistance is achieved at 76 K with a critical current density of 3700 A/cm2at 30 K.

ISSN:0021-8979    

DOI:10.1063/1.346698

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

As‐deposited superconducting thin films of Y1Ba2Cu3O7−&dgr;are grown using, for the first time, a Nd:YAG laser (&lgr;=1.06 &mgr;m) at substrate temperatures &bartil;450–500 °C in the presence of dc plasma of O2on SrTiO3substrates (100 orientation). We find that the conventional ring electrode geometry used by others does not have the desired effect with Nd:YAG lasers. We use a simple disc electrode to generate O2plasma.

ISSN:0021-8979    

DOI:10.1063/1.346678

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe first results for deuterium effusion from undoped and doped crystalline silicon (n‐ andp‐type) treated in a D2plasma under different conditions. The dependence of the effusion spectra on doping level, passivation temperature, sample bias, and preannealing are presented and the results are discussed on the basis of different D‐bonding configurations in the passivated silicon samples.

ISSN:0021-8979    

DOI:10.1063/1.347156

出版商:AIP    

年代:1990

数据来源: AIP