Effects Of Disk Structure Research Articles

Magnetoresistance effect of p-type diamond films in various doping levels at different temperatures

Abstract The magnetoresistance effect of p-type diamond films has been investigated at different temperature. Diamond films were grown by microwave plasma chemical vapor deposition. Mirror-polished p-type Si(100) was used as a substrate material. The experimental results show that a notable magnetoresistance effect in polycrystalline and heteroepitaxial semiconducting diamond films was observed. The relative changes in the resistivity of the diamond films with magnetic field strongly depended on both boron-doped concentration in the films and geometric form of the samples. The effect of disk structure was greater than that of strip-type samples, also variation in the resistivity of heteroepitaxial diamond films was greater than that of polycrystalline diamond films at same magnetic field. The magnetoresistance of p-type diamond films was decreased with increasing both boron-doped concentration and temperature. The relative changes in resistance of the heteroepitaxial diamond films with the disk structure was increased by 0.85 at room temperature under magnetic intensity of 5T, but only 0.40 for strip-type structure. The results are discussed in detail.

Enhanced Transverse Magnetoresistive Effect in Semiconducting Diamond Films

A very large magnetoresistive effect in both homoepitaxial and heteroepitaxial semiconducting diamond films by chemical vapor deposition has been observed. The changes in the resistance of the films strongly depend on both magnetic field intensity and geometric form of the samples. The effect of disk structure is greater than that of stripe type samples, also variation in the resistance of homoepitaxial diamond films is greater than that of heteroepitaxial diamond films. The resistance of homoepitaxial diamond films with the disk structure is increased by a factor of 2.1 at room temperature under magnetic field intensity of 5 T, but only 0.80 for heteroepitaxial diamond films.

Line Emission from an Accretion Disk Around a Black Hole: Effects of Disk Structure

The observed iron K-alpha fluorescence lines in Seyfert-1 galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. These lines serve as powerful probes for examining the structure of inner regions of accretion disks. Previous studies of line emission have considered geometrically thin disks only, where the gas moves along geodesics in the equatorial plane of a black hole. Here we extend this work to consider effects on line profiles from finite disk thickness, radial accretion flow and turbulence. We adopt the Novikov and Thorne (1973) solution, and find that within this framework, turbulent broadening is the dominant new effect. The most prominent change in the skewed, double-horned line profiles is a substantial reduction in the maximum flux at both red and blue peaks. The effect is most pronounced when the inclination angle is large, and when the accretion rate is high. Thus, the effects discussed here may be important for future detailed modeling of high quality observational data.

READING DYNAMICS IN MAGNETIC SUPER RESOLUTION MEDIA

Reading dynamics in front aperture detection (FAD) and center aperture detection (CAD) magnetic super resolution (MSR) media is studied using a high speed Kerr microscope system with 10-ns resolution. The effects of disk structure and reading conditions on the reading dynamics are investigated. Readout of 0.2 micron domains is successfully demonstrated using 488 nm wavelength light on CAD MSR media.