摘要:

Temperature dependent growth of Mn on GaAs(001) and their interface structure have been studied. At 400 K, fcc Mn grows epitaxially on GaAs and a“Mn2As-type” Mn–Ga–As mixed layer sandwiched between the fcc Mn and GaAs(001) is observed. It is this transition layer that plays a critical role in the stabilization of the metastable fcc-Mn-phase on GaAs(001).©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118854

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The thermomodulation spectrum from metal organic chemical vapor deposition grown GaN has been measured in the temperature range of 20–310 K. A theoretical model is established to explain the spectrum by considering the modulation of dielectric constant and epilayer thickness. It is found that the latter is especially important for a material system with a large difference in refractive indices between the epilayer and the substrate. The band gap energy and broadening parameter are determined using a lineshape analysis. Varshni coefficients of the energy gap are determined. The temperature dependence of broadening parameter is also measured. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118855

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We observed persistent photoconductivity inYBa2Cu3Oxbicrystal grain boundary Josephson junctions. Upon illumination of these grain boundary Josephson junctions, the normal state resistance decreases and the critical current increases. This strongly suggests that the grain boundary in these films consists of oxygen depletedYBa2Cu3Ox.A comparison with the persistent photoconductivity in oxygen depletedYBa2Cu3Oxthin films implies an average oxygen content ofx=6.6±0.1for the grain boundary. The spectral dependence has a lower threshold for persistent photoconductivity in the junctions(≈1.2 eV) than in thin films. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118856

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This letter describes a method for producing conducting microcoils for high resolution proton nuclear magnetic resonance(1H-NMR) spectroscopy on nanoliter volumes. This technique uses microcontact printing and electroplating to form coils on microcapillaries. Nuclear magnetic resonance spectra collected using these microcoils, have linewidths less than 1 Hz for model compounds and a limit of detection (signal-to-noise ratio=3) for ethylbenzene of 2.6 nmol in 13 min. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118857

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A selective electrodeposition method for the fabrication of extremely thin and long metallic and magnetic wires is introduced. Growth is done on the cleaved edge of a semiconductor multilayer structure incorporating a 4-nm-wide modulation doped quantum well. This conducting quantum well is connected to the negative current contact during electrodeposition. Since electrodeposition requires the neutralization of positive metal ions from the solution, deposition takes place selectively onto the edge of the quantum well, leading to the fabrication of extremely thin magnetic metal wires, which should be useful for the investigation of the limits of magnetic storage. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118858

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In an attempt to identify the driving force for the formation of chains composed of nanometer size Fe alloy particles that were recently reported, experiments have been carried out with the magnetic metals Fe, Co, and Ni and a nonmagnetic metal Cu. The samples obtained by a reduction of aqueous metal chloride solutions with potassium borohydride have been characterized by x-ray diffraction, transmission electron microscopy, and superconducting quantum interference device magnetometer measurements. The results reveal that the magnetic interaction between the adjacent particles plays a determining role in the chain structure formation. Although both crystallinity and boron content do not play a direct role, they influence significantly the magnetic properties, and thereby have an indirect role in the formation of the chain structures. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118859

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have succeeded in growing epitaxial (0001) MnSb/(111)B GaAs films with an atomically flat heterointerface using a GaAs buffer layer. For MnSb films with a thickness of 2–20 Å, the in-plane strain in the films arising from a lattice mismatch between MnSb and GaAs is compressive, which was observed byin situreflection high-energy electron diffraction measurement. On the other hand, a rough interdiffused interface was obtained in samples grown without a GaAs buffer layer. In contrast to the case of samples with flat interfaces, the in-plane strain is tensile, which is attributed to interdiffusion of Sb into GaAs substrates. The magnetization of the MnSb films with the thickness of this range shows a strong dependence on the interface quality. The saturation magnetization and the saturation magnetic field of the samples with the rough interface are smaller than those of the samples with the atomically flat interface. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118860

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Orientational optomechanical media, consisting of three dimensional arrays of elongated metal coated dielectric beams suspended by torsional springs, was fabricated using microelectromechanical system (MEMS) technology. Response of a single rotating element to a polarized electromagnetic radiation was found to be in a good agreement with theory. Spatial grating formation in fabricated orientational optomechanical media was detected and measured under the influence of two orthogonally polarized electromagnetic fields at 15 GHz. This process demonstrates the feasibility of using optomechanical media for phase conjugation, via degenerate four-wave mixing, and for other nonlinear processes at microwave and millimeter wave frequencies. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118861

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Optical emission spectroscopy with high spatial resolution was applied for the study of plasma–material interaction in low-pressure reactive ion etching. Atomic and molecular emission by sputtered material has been found to be strongly localized near the surface. Excited particles are produced during sputtering by energetic ions, with the mechanisms being different for atoms and molecules. In atomic secondary photon emission, a cascade from highly excited levels is shown to be important. This method can be used as a probe during plasma processing. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118862

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.119269

出版商:AIP    

年代:1997

数据来源: AIP