| Summary: | 博士 === 國立交通大學 === 電子物理系所 === 92 === Dynamical behaviors of two oscillatory many body systems have been investigated. From a classical nonlinear resonance or phase-locking point of view, we firstly discuss the similarity between two macroscopic quantized systems, namely the driven superconductive Josephson ac effects and the quantized Hall effects. The other system under study involves the correlation between the reflection high energy electron diffraction intensity of interrupted STO laser deposition and the kinetic characteristics of the surface step edges.
The I-V characteristics of the Shapiro steps of a 2 dimensional superconductive Josephson junction can be described by the Resistively and Capacitively Shunted Junction (RCSJ) model. The governing equation is equivalent to a periodically driven nonlinear oscillator. When the system falls into the phase-locked state, the natural frequency and the external frequency lock in an integer or a rational ratio. Under a postulate of dynamic macroscopic quantization, the quantized Hall effects have been modeled with a periodically forced oscillation as the rf driven Josephson ac effects. The Hall voltage steps can be obtained as a ratio between the reciprocal of fine structure constant and the frequency of the electro-magnetic oscillation.
The relation between the RHEED intensity oscillation and the 2-dimensional layer by layer growth was another macroscopic dynamical system under investigation. During the in-situ recording on the constant-temperature annealing of interrupted laser ablation Strontium Titanate, we found quantitative correlation between the RHEED intensity and the density of the line dislocations on the surface. By drawing the diffusion Arrhenius plot directly from the RHEED intensity we obtained a reasonable value for the activation energy of the isolated step edge migration. In a series of RHEED experiments with different heating rates for room temperature deposited films, a higher activation energy is obtained from the Kissinger plot. These two activation energies together suggest two different smoothening mechanisms during the recovery of the RHEED intensity in the Epitaxy growth. Analyses directly on the RHEED intensity not only gives us the kinetics of diffusion, but also provides inspiring supports for the dynamic model describing the RHEED intensity.
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