Volume 92, Issue 2, 15 July 2002
Index of content:
92(2002); http://dx.doi.org/10.1063/1.1486026View Description Hide Description
Cubic zinc blende CdS epilayers were grown on (100) GaAs substrates by hot-wall epitaxy. The lattice constant of cubic CdS was measured by x-ray diffraction and it was found that the compressive strain remained in the CdS films. Photoluminescence(PL)measurement showed the free exciton emission at the room temperature. Room temperature energy gap and exciton binding energy were determined by absorption and PLspectra.
Electrochemical tuning of band structure of single-walled carbon nanotubes probed by in situ resonance Raman scattering92(2002); http://dx.doi.org/10.1063/1.1486024View Description Hide Description
In situ resonance Raman scattering of single-walled carbon nanotubes investigated under electrochemical biasing demonstrates that the intensity of the radial breathing mode varies significantly in a nonmonotonic manner as a function of the cathodic bias voltage, but does not change appreciably under anodic bias. The tangential mode is, however, not affected. These results can be quantitatively understood in terms of the changes in the energy gaps between the one-dimensional van Hove singularities in the electron density of states arising possibly due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms.
92(2002); http://dx.doi.org/10.1063/1.1489709View Description Hide Description
We present a simple method using direct laser beam reflection from the MgO substrate of a PBN:65 thin film to measure strain–electric field hysteresis produced by electric field-induced bending. We obtained both the strain–electric field and time–electric field relationships from these hysteresis curves. In addition, we determined time constants for strain saturation, obtained a quadratic relationship between strain and electric field, and calculated a value of 0.000 875 μm2/V2 for the electrostrictive constant.
92(2002); http://dx.doi.org/10.1063/1.1489088View Description Hide Description
Giant magnetoresistance(GMR) of 3.5% in low fields of about 10 Oe was observed at room temperature in as-prepared laser-deposited (permalloy/Ag) multilayers. Strong columnar growth in combination with preferential sputtering of Ag from the film surface during deposition of layer helps to directly create a discontinuous multilayerstructure necessary for high GMR values. The magnetoresistance was found to increase to 5.1% after annealing for just 10 min at 275 °C. This increase is attributed to structural relaxation processes such as demixing of the intermixed interfaces, preferential diffusion of Ag to the column boundaries and reduction of structural defects. Pulsed laser deposition appears to be a suitable technique for the preparation of permalloy/Ag films with considerable GMR in a one-step process.