摘要:

A phase distortion method is applied to examine the optical nonlinearity in tellurium dioxide single crystal. The positive nonlinear index of refraction is observed in the crystal at above the two‐photon absorption edge. While the observed positive sign is consistent with that predicted theoretically, the absolute values of both nonlinear index of refraction and two‐photon absorption coefficient are larger than the theoretical values by a factor of five. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359653

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The compositional distribution in fcc Co‐Mn magnetic thin films was studied in order to examine the possibility of a compositional separation, similar to that observed previously in hcp Co‐Cr thin film magnetic recording media, occurring in an fcc alloy system. Spin‐echo59Co NMR study of Co75Mn25films revealed a change from a homogeneous compositional distribution in a film deposited at a substrate temperature (Ts) of RT to a compositionally separated state in a film deposited at a Ts of 300 °C. Vibrating sample magnetometry revealed an associated three‐fold enhancement in saturation magnetization in the films deposited at a Ts of 300 °C. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359654

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An analytical approximation for the electron density in the conduction band of the entire Hg1−xCdxTe (MCT) alloy system (0<x<1) as a function of the composition, temperature and Fermi energy location, is proposed. A hyperbolic expression for the conduction band is shown to yield an error which is practically not larger than Kane’s model in the entire composition range of MCT. The analytical approximation is compared with a numeric calculation of the Fermi‐Dirac integral using this hyperbolic band approximation, and shows a deviation of a few percents for temperatures in the range 2<T<300[K], compositions in the entire range 0<x<1 and electron densities up ton=1020[cm−3]. This analytical approximation can be extremely useful for numerical band diagram and transport simulations of graded and abrupt MCT heterojunctions and devices. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360735

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The current density of electrons emitted from surfaces irradiated by light is known to follow either a linear or quadratic dependence with intensity for single‐ or double‐photon absorption respectively or, at high incident light intensities, a square root dependence (depressed photoemission). In separate experiments, a Go¨rlich (Cs3Sb) cathode was irradiated with the green (&lgr;=5140 A˚) and blue (&lgr;=4880 A˚) lines of an Ar+laser at various intensities in an effort to determine over what range depressed photoemission continued above the current density threshold of about 10−5A cm−2. The results have confirmed and extended the existence of depressed photoemission to intensities of up to five orders of magnitude higher than previously observed threshold values with no apparent evidence of saturation of the effect. The consequences of this are discussed in relation to surface traps and two‐photon‐plasmon excitation in the photocathode. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359655

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

High‐TcYBa2Cu3O7rf superconducting quantum interference devices made by oxygen‐ion modification have been produced and used successfully since 1990, but the mechanism of their operation remains still unclear. Reported is a computer modeling of the ion modification using theTRIMprogram. It appears that the depression of the transition temperature is responsible for the operation of these bridges as weak links. At 77 K and modeling using our experimental parameters, only the base of the YBa2Cu3O7film about 50 nm thick near the substrate is superconducting, which acts as a weak link probably because of the temperature‐dependent coherence length near the reduced transition temperatureT′cof the modified material. ©1995 American Institute of Physics. 

ISSN:0021-8979    

DOI:10.1063/1.359656

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A recent article by Dandekar, Abbate, and Frankel [J. Appl. Phys.76, 4077 (1994)] reviews existing data on high‐pressure properties of aluminum nitride (AlN) in an effort to build an equation of state for this material. A rather large portion of that article is devoted to the shear strength of AlN and, in particular, to our data of 1991 with longitudinal and lateral stress gauges [Z. Rosenberg, N. S. Brar, and S. J. Bless, J. Appl. Phys.70, 167 (1991)]. Since our highest data point has an error of 1 GPa, much of the discussion and conclusions of Dandekar and co‐workers are not relevant once this error in data reduction is corrected. We also discuss the relevance of our shear strength data for various issues, such as the phase transformation of AlN at 20 GPa and the general shape of Hugoniot curves for brittle solids. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359620

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This reply reinforces the need for examining the internal consistency of longitudinal and lateral stress data under plane shock wave propagation. This was pointed out in an article by Dandekar, Abbate, and Frankel [J. Appl. Phys.76, 4077 (1994)] to determine the shear strength of a solid. It also shows that shear strength of a crystalline solid under plane shock wave compression can be determined accurately from its reliable Hugoniot and applicable hydrodynamic compression of the solid.

ISSN:0021-8979    

DOI:10.1063/1.359621

出版商:AIP    

年代:1995

数据来源: AIP