摘要:

Secondary ion mass spectroscopy (SIMS) and Fourier transform infrared (FTIR) absorption have been studied in thin oxides ofSi1−xGexgrown by plasma oxidation. SIMS analysis reveals that Ge can migrate to the oxide film surface leaving the oxide in the SiGe interface region Ge-depleted. This is in contrast to thermally grown oxides. Water selectively attacks the Ge-rich part of the oxide. In the FTIR spectra of the SiGe oxides, specific peaks identified with the vibration of O in Si–O–Ge and Ge–O–Ge bonds have been observed for the first time. These latter observations confirm that for the plasma oxidized films, the Ge is chemically bonded in the oxide network. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121078

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Measurements of the magnetoresistanceR(H)as functions of the temperature and the angle &thgr; between the applied magnetic field and the plane of a(Bi,Pb)2Sr2Ca2Cu3O/Agtape have been performed in a low magnetic field region belowTc.Contrary to the two-dimensional vortex pancake model, the data do not scale well withH sin(&thgr;)for small angles. Instead, our results show a general three-dimensional scaling behavior based on the anisotropy in the upper critical fieldHc2over entire angular range. From the scaling, the dissipation anisotropy is found to be unchanged at lower temperatures and decreases with increasing temperature at temperatures close toTc.©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121079

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Basic characteristics of a simple single-flux-quantum (SFQ) logic gate using high-Tcmaterial and Josephson junction (NdBa2Cu3O7−&dgr;and focused ion beam junction) have been investigated. The logic gate consists of an rf-superconducting quantum interference device (rf-SQUID) and a dc-SQUID. In the logic gate, elementary SFQ logic operations, such as generating SFQ (dc/SFQ) and providing simultaneous readout (SFQ/dc), have been confirmed up to 50 K. The temperature dependencies of the output voltage level and the critical current-normal resistance(IcRn)product were compared, and the decreasing tendency of the output voltage level for increasing temperature was found to be more rapid than that of theIcRnproduct. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121080

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A magnetic resonance force microscope with a “tip-on-cantilever” configuration was used to compare imaging characteristics of paramagnetic and ferromagnetic samples. Three-dimensional electron paramagnetic resonance (EPR) imaging of diphenylpicrylhydrazil (DPPH) particles was accomplished by scanning the sample in two dimensions while stepping an external field. The EPR force map showed broad response reflecting the size and shape of the sample, allowing a three-dimensional real-space magnetization image to be successfully reconstructed. In contrast to the EPR case, ferromagnetic resonance imaging of a micron-scale yttrium iron garnet sample showed no significant line broadening despite the strong field gradient(∼10 G/&mgr;m).Two-dimensional force maps revealed spatial dependence of magnetostatic and magnetoelastic modes. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121081

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report on the growth of single-crystal Fe films by magnetron sputtering onto GaAs substrates. In order to establish the epitaxial orientation with the substrate a 100 Å Cr buffer layer was rf sputtered. The crystalline and magnetic properties were studied by x-ray diffraction, ferromagnetic resonance, and Kerr effect magnetometry techniques. The &thgr;-2&thgr; x-ray measurements show that only the Fe (200) peak is present, and the rocking curve shows a full width half maximum of 2°. Ferromagnetic resonance lines exhibit a line width of about 30 Oe, and the in-plane resonance field as a function of the azimuth angle presents a fourfold symmetry with no induced anisotropy. The in-plane hard- and easy-axis magneto-optical hysteresis loop traces are consistent with the ferromagnetic resonance results. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121082

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The size, shape, and polarization orientation of fatigued areas formed during the suppression of the switchable polarization(Prs)(fatigue) in Pt–PZT–Pt ferroelectric capacitors (FECAPs), were observed by means of atomic force microscopy and by imaging the phase of the piezoelectric vibration induced by a low ac field applied between the top and bottom electrodes. In the virgin state (FECAP as prepared), the pattern of the polarization domains with opposite orientation was randomly distributed with typical sizes of 1–3 &mgr;m. The application of a dc field larger than the coercive field(Ec)enabled to fully orient the polarization of the regions in either directions. During the initial fatigue (<35&percent; of suppressedPrs), polarized regions with frozen orientation and size ranging between 100 nm and 1 &mgr;m became visible. In the fatigued state (>65&percent; of suppressedPrs), two main configurations of the frozen polarization domains were distinguished. One was characterized by a strong preferential direction (top to bottom electrode) and the other by randomly distributed regions of opposite oriented frozen polarization. The degrees of fatigue obtained by analyzing the vibration phase images are in good agreement with those obtained by standard polarization measurements. It is concluded that thePrssuppression (fatigue) is due to “region by region” or “grain by grain” freezing ofPrsand that the frozenPrscan have a preferential orientation. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121083

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.121084

出版商:AIP    

年代:1998

数据来源: AIP