摘要:

We report the fabrication of high-Tcsuperconducting wires by photodoping aGdBa2Cu3O6.5thin film. An optical near-field probe was used to locally excite carriers in the system at room temperature. Trapping of the photogenerated electrons define a confining potential for the conducting holes in the CuO planes. Spatially resolved reflectance measurements show the photogenerated nanowires to be ∼250 nm wide. Electron diffusion, before electron capture, is believed to be responsible for the observed width of the wires. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121787

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have modeled the generation of a voltage signal in noncontact potentiometric scanning force microscopy for a locally enhanced potential due to an isolated patch of electrostatic charge on an insulating surface. Both the distribution of the charge and the dielectric nature of the insulator is taken into account. When the charge is assumed to disperse ohmically on the surface, a complex time-dependent decay in the signal occurs. The profile of the decay predicted by this assumption has a shape similar to that observed experimentally in submicron scale contact charging experiments. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121788

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The electrical and microstructural properties of pure strontium bismuth niobate (SBN) prepared by spin coating have been examined. Randomly ordered films have larger dielectric constants and remanent polarization values (maximum ofPr=12.5 &mgr;C/cm2) than doc-axis oriented films. The heretofore unexplained dependences ofPrupon Sr content in SBN and SBT is shown to be entirely due to the sensitivity of grain orientation to Sr content in SBN. Vertical shifts (Paxis) in the hysteresis curves are eliminated via ozone anneals. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121705

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Evidence is presented of the dynamic nucleation of ice induced by an isolated stable cavitation bubble in undercooled water. The evidence supports the notion of dynamic nucleation as a result of the freezing point shift due to high pressure pulses associated with a collapsing bubble. It is found that the cavitation bubble requires minimum undercooling, 5 K, to initiate nucleation on ice. This undercooling may be attributed to the temperature rise of the water due to the heat generated by compression of the bubble or the undercooling required for normal ice to nucleate on a high pressure phase. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121706

出版商:AIP    

年代:1998

数据来源: AIP