|Budget Amount *help
¥2,700,000 (Direct Cost : ¥2,700,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥2,100,000 (Direct Cost : ¥2,100,000)
Due to the enhanced effect of fluctuations, the problem of the phase diagram of high-TィイD2cィエD2 superconductors in applied magnetic fields is highly nontrivial and has attracted much recent interest. For random type-II superconductors with point disorder, possible existence of an equilibrium thermodynamic phase called the vortex-glass phase, where the vortex was pinned on long length scale by randomly distributed point-pinning centers, was proposed. In the project, stability of the three-dimensional vortex-glass order in random type-II superconductors with point disorder is investigated by equilibrium Monte Carlo simulations based on a lattice XY model with a uniform field threading the system. It is found that the vortex-glass order, which stably exists in the absence of screening, is destroyed by the screening effect, corroborating the previous finding based on the spatially isotropic gauge-glass model. Estimated critical exponents, however, deviate considerably from the values reported for the gauge-glass model.