摘要:

Magnetoimpedance in as‐cast, nonmagnetostrictive CoFeBSi amorphous ferromagnetic wires, submitted to an ac electric current of 5 mA in the frequency range 100 Hz–100 kHz, is analyzed in terms of equivalent circuits. It is shown that the equivalent circuit representing the wire frequency behavior can be approximated by a parallelLpRparrangement with elementsRsandLsin series;LpandRpare associated with circumferential domain wall permeability and wall damping, respectively;Lsis related to the circumferential rotational permeability of the wire, andRsaccounts for the dc resistance in the circuit. When the wire is submitted to a longitudinal dc field high enough to approach saturation (Hdc=3600 A/m), the circuit becomes simply a seriesRsLscircuit. The various contributions from basic magnetization processes to magnetoimpedance are discussed, as well as deviations from this idealized model. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359756

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The energy relaxation of excitons in the organic semiconductor tetracene (film thickness 160 nm) is studied by photoluminescence from 15 to 300 K using time‐correlated single‐photon counting. The well‐known relaxation of triplet excitons with time constant ∼7 ns is accompanied by a faster relaxation process with time constants ranging from 260 ps to 1.2 ns, depending on temperature and wavelength. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359757

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Negative ions extracted from a pulsed rf discharge can have a complex energy dependence as a function of time. This dependence could influence semiconductor processing in pulsed discharges, particularly if precise control of the ion energy is important. In this article, the time‐dependent ion energy distributions of F−from pulsed discharges through CF4are presented for the first time using a mass spectrometer equipped with a Bessel Box energy analyzer. The time‐dependent changes in the ion energy distributions are produced by the manner in which the plasma disintegrates. Negative ions reaching the processing surface very early in the afterglow have lower energies because they experience less acceleration by the dc bias potential before entering the mass spectrometer. These ions appear in a very intense, short duration pulse, suggesting that they are formed in the after glow near the entrance to the mass spectrometer. Ions reaching the surface later in the afterglow have higher energies because they travel further through the dc bias potential. These ions appear with less intensity over a longer period of time. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360682

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Optical transmissions were studied for Fe/MgF2multilayered thin films whose total Fe thickness is kept at 1000 A˚. The optical transmission at 700 nm was 26%, and 67% at 2000 nm for films with 15 A˚ Fe layer thickness. These transmissions were almost proportional to the inverse of the Fe layer thickness. The Maxwell‐Garnett model can be a possible mechanism for the granularlike multilayer, for example, the (15 A˚/30 A˚) 70 film; however, transmissions were also enhanced in films with continuous Fe layers. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359693

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have studied the oxidation in water vapor of thick (0.5–2 &mgr;m) AlGaAs layers with aluminum contents ranging from 48% to 78% grown by molecular beam epitaxy. The oxidation rate was measured as a function of the aluminum content, the temperature and the flow rate of the N2carrier gas supplying the water vapor. The oxide films proved to be mechanically very stable and the growth was found to be linear with time also in the case of an excessive supply of water vapor. The activation energies for the wet oxidation of AlGaAs were determined to increase from 1.1 to 1.8 eV for the Al contents decreasing from 78% to 48%. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360736

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have found evidence through optical spectroscopy that AgO is indeed generated in the laser plume during pulsed laser deposition of YBa2Cu3O7−&dgr;(YBCO) thin films using Ag‐doped YBCO targets. This supports our earlier conjecture that formation of AgO in the plume and its subsequent dissociation at the elevated substrate temperature (since AgO is unstable above 350 °C) provides active oxygen to the YBCO lattice, thereby increasing oxygen incorporation during growth of YBCO thin films. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359694

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Photoluminescence (PL) measurements carried out between 10 and 140 K on Cu‐diffused InP showed the presence of the Cu band at 1.216 eV. From the temperature variation of PL intensity the activation energy for the quenching was found to be 77.4 meV. The line shape, linewidth, and configuration coordinate diagram of the defect band have been calculated. The vibration energy of the excited state was found to be 14 meV from linewidth analysis. A coupled phonon energy of 38 meV and a Huang–Rhys factor of 2.13 were obtained from line‐shape analysis. The displacement of the excited state minimum from the ground state was found to be 0.079 A˚ which showed that the lattice relaxation of the Cu‐related defect in InP is small. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359695

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Recently W. Kissinger, M. Weidner, H. J. Osten, and M. Eichler [Appl. Phys. Lett.65, 3356 (1994)] reported ellipsometry and electroreflectance measurements on theE0,E1, andE2critical point energies in strained Si1−yCyalloys grown pseudomorphically on Si (001) using molecular‐beam epitaxy. We present a theory explaining these energies using established deformation‐potential theory and interpret the results and their implications for the band structure of these alloys. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359696

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Measurements of the temperature dependence of the normal state resistivity, &rgr;n(T), for (R0.8Pr0.2)Ba2Cu3O7−&dgr;(R=Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Yb) are reported. We found that &rgr;nis linearly dependent on the temperature (except R=Nd). At a constant temperature, &rgr;nis linearly dependent on the ionic radius of R. The results are interpreted in terms of the hybridization between the local states of the Pr ion and the valence‐band states of the CuO2planes. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359697

出版商:AIP    

年代:1995

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.360786

出版商:AIP    

年代:1995

数据来源: AIP