摘要:

The microstructure at the interface between YBa2Cu3O7(YBCO) thin film and (100)LaAlO3substrate has been investigated by using transmission electron microscopy. It has been observed that two distinct microstructural features existed in the interface: (1) A thin transitional layer of Ba3Al2O6was frequently observed and the YBCO thin film grown on it showed stacking faults. (2) Sharp interface with no transitional layer was also occasionally observed and the YBCO film grown on it was single crystalline. In rare cases, a low symmetry phase was observed near the surface of the LaAlO3substrate, however, the distortion caused by the lattice mismatch between this phase and the YBCO did not affect the quality of the YBCO thin film. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113756

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Insituhigh‐temperature x‐ray measurements have been used to follow the crystallographic changes that occur as Pb‐doped Bi2Sr2Ca1Cu2O8+&dgr;plus other phases transform to Bi2Sr2Ca2Cu3O10+&dgr;in a powder‐in‐tube process for forming tape conductors. On the initial ramp to the reaction temperature, the Bi2Sr2Ca1Cu2O8+&dgr;x‐ray lines first diminish in amplitude, by about a factor of 2 or more, and then begin to grow again above 700 °C. In the 790–795 °C range, a transient new phase is seen. Finally, at temperatures as low as 790 °C, the Bi2Sr2Ca2Cu3O10+&dgr;phase begins to grow as the Pb‐doped Bi2Sr2Ca1Cu2O8+&dgr;disappears. Separate studies of a Pb‐doped Bi2Sr2Ca1Cu2O8+&dgr;pellet without the Ca2Cu1O3and CuO present show essentially the same peak intensity changes during the temperature ramp to 700 °C. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113757

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

C‐axis oriented YBa2Cu3O7−x(YBCO) thin films were deposited by an ozone‐assisted reactive coevaporation method and characterized byinsitulow‐energy ion scattering spectroscopy (LEISS). We successfully evaluated compositional information in depth by an angle‐resolved LEISS method and a depth profiling LEISS method. These LEISS analyses indicated that the second outermost layer of the YBCO surface consisted of Ba atoms. This result confirmed that YBCO surfaces were terminated by Cu(1)‐O chains. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113758

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have simulated fluxon propagation within a Josephson transmission line that is one of the elements of a rapid single flux quantum (RSFQ) circuit. This line is a parallel connection of damped Josephson junctions coupled by superconducting inductances. Geometries with and without mutual inductances between neighboring cells are considered. If the time interval between two fluxons is less than 0.3 &fgr;0Vc−1(Vccharacteristic voltage) a repulsion between them was observed. The repulsion sets a specific time delay between the fluxons that impose a rigid limitation for high frequency performance of RSFQ logic. The delay depends on the shunting parameter, bias current, and values of interconnecting inductances. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113759

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The use of soft x‐ray magnetic circular dichroism in two‐dimensional (2D) element‐specific vector magnetometry is demonstrated by investigating a thin Fe(001) single‐crystal film grown on ZnSe(001). By measuring element‐specific magnetic hysteresis curves along directions parallel and perpendicular to an applied magnetic field, the 2D behavior of the in‐plane magnetization vectorMis described as a function of the applied magnetic field. The use of this method to obtain element‐specific 3D vector magnetometry in magnetic materials that exhibit both in‐plane and out‐of‐plane magnetization is also discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113760

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Single‐crystal films of perovskitelike (La,Ca)MnO3with very smooth surface were grown epitaxially on (110) NdGaO3substrates by a simple facing‐target sputtering technique. Their in‐plane and out‐of‐plane crystal structures were examined by means of a novel double‐crystal x‐ray diffraction technique. Thecaxis of the samples lay in the film plane. All rocking curves were found to have a full width at half‐maximum of about 0.01° which is smaller than all reported structure data for ceramic thin films. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113761

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We demonstrate a versatile capability to measure directly the magnetostrictive properties through the magnetization process on a nanometric scale using a modified scanning tunneling microscope. Single 10 mm long, 125 &mgr;m diam amorphous wires of both positive and negative magnetostriction have been studied and the data are compared with the hysteretic loops determined by both ac and SQUID magnetic measurements. This improved technique promises interesting possibilities, from both fundamental and applications points of view, in a number of scientific disciplines especially of interest in life and environmental sciences. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113762

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We presentabinitioelectronic structure calculations for (Pt/Co/Pt)/X superlattices with X = Pd, Ag, or Cu. Large intrinsic perpendicular magnetic anisotropies, as compared to similar Co/X superlattices, are predicted. On average, the calculated anisotropies decrease in the order Pd ≳ Ag ≳ Cu. In particular, the anisotropy of (1Pt/1Co/1Pt)/1Pd, 3.2×108ergs/cm3(Co), is three times larger than that predicted for either 1Co/3Pt or 1Co/3Pd. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113763

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Polycrystalline diamond films have been grown on silicon at substrate temperatures down to 300 °C in a 3 Torr CH4–H2–O2microwave plasma. The diamond films exhibit characteristic 1333 cm−1Raman phonon peaks with linewidths of 3–7 cm−1and a small nondiamond carbon response. Low temperature diamond synthesis was enhanced by applying a static magnetic field to increase gas dissociation and ionization, and by pulse modulating the 2.45 GHz input microwave power to provide a large atomic hydrogen supply without accompanying positive ion bombardment over most of the discharge cycle. Diamond quality is improved and growth rates are at least an order of magnitude higher in the pulsed mode, compared to continuous wave operation with the same average input microwave power. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113764

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Clear Coulomb blockade effects have been observed in lateral metal nanostructures fabricated by combined electron beam lithography and ionized beam deposition. Islands between 2 and 3 nm in diameter were formed in a 25 nm gap for which the effective tunneling capacitance is calculated to be 0.2 aF. Clear Coulomb gaps and staircases were observed at 77 K in current–voltage characteristics. The staircases can still be seen at room temperature but the gaps tend to a nonlinearity inI–Vcharacteristics around zero bias voltage. The total device area is about 0.01 &mgr;m2. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113765

出版商:AIP    

年代:1995

数据来源: AIP