摘要:

Because of the magnetic surface charge, the wall magnetization is ``twisted'' into a direction almost perpendicular to the wall plane near the film surface. The width and energy of such walls and the twist angle have been calculated by a variational method for uniaxial anisotropy and stationary plane walls. For very thick films (film thickness ≫ wall width in an infinite medium), the reciprocal wall width and the wall energy are smaller than the values for an untwisted wall by approximately a factor (1 − 0. 65&sgr;)½, where &sgr;=4&pgr;M0/Ha,M0being the saturation magnetization andHathe uniaxial anisotropy field.

ISSN:0003-6951    

DOI:10.1063/1.1654355

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

An electroacoustic transducer array employing condenser‐microphone elements with a solid dielectric diaphragm is described. Both diaphragm and backplate of the array are selectively metallized on one side along parallel strips and positioned so that the metal strips of the diaphragm are perpendicular to the metal strips of the backplate with the dielectric foil separating the two. The areas of overlapping diaphragm and backplate strips form identical condenser microphone elements. The array is mechanically and electrically simple, is capable of operation in gases and liquids over wide frequency ranges, and can be designed with large apertures. The overlapping metal‐strip technique can also be employed for piezo‐electric arrays.

ISSN:0003-6951    

DOI:10.1063/1.1654356

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The carbonization of certain cross‐linked polymers under carefully controlled conditions yields a nongraphitizing carbon which, on account of its high lustre and conchoidal fracture, has been called ``vitreous carbon''. The temperature coefficient of resistivity for this carbon has been determined and its bulk resistivity reconfirmed. These are compared to carbons formed from other bases, and it is shown that, although vitreous carbon has unique mechanical properties, its electrical characteristics are similar to a common form of processed carbon.

ISSN:0003-6951    

DOI:10.1063/1.1654357

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Experimental results are presented on conduction, breakdown, and switching in Al&sngbnd;SiO2&sngbnd;Si MOS dots. Transitions from the low‐conduction state are found to terminate in self‐healing breakdowns. There also exists a higher‐conduction state in which destructive breakdowns do not occur.

ISSN:0003-6951    

DOI:10.1063/1.1654358

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A niobium helix‐resonator cavity close to the frequency suitable for a heavy‐ion accelerator has been subject to an 8‐week test, including 323 h at full power (axial electric fieldEax>2.5 MV/m). The cavity, with an anodically deposited protective film of Nb2O5, had a highQand supported high fields without deterioration over the whole period during which it was subject to a moderate internally generated x‐ray dose. Properties were found to be stable against considerable thermal cycling and exposure to air. Measurement of emitted x‐ray maximum energy allowed an independent corroboration of the field measurement calibration.

ISSN:0003-6951    

DOI:10.1063/1.1654359

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The ultraviolet photoemission technique has been applied to the study of the oxidation of strontium and cerium. It has been found that the photoemission measurement provides a method to determine the oxide growth rate perpendicular to the surface, the composition of the surface, and the stable oxide phases formed during the oxidation process.

ISSN:0003-6951    

DOI:10.1063/1.1654360

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

This letter reports for the first time the detection of infrared radiation emitted from a metal‐to‐metal point‐contact diode as the result of mixing the frequencies of the radiation fields applied to the diode.

ISSN:0003-6951    

DOI:10.1063/1.1654361

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Two stages in the relaxation process for conical‐helical perturbation in cholesteric liquid crystals are seen when a dc electric field is applied. The second stage, which is accompanied by the growth of optical rotation with time, is relatively long. By replacing the dc field with a 30‐ to 60‐Hz ac field, this long relaxation stage can be eliminated and the total relaxation time is shortened. However, this also causes the response time to become longer, as compared to the response to a dc field. A four‐electrode cell and an ac‐dc combined technique is described by which both advantages of rapid response and relaxation times are achieved.

ISSN:0003-6951    

DOI:10.1063/1.1654362

出版商:AIP    

年代:1972

数据来源: AIP