|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1996 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1995 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1994 : ¥1,100,000 (Direct Cost : ¥1,100,000)
In Frustrated systems with continuous degrees of freedom, which have competing interaction between constituent elements, new 'chiral' degrees of freedom often appear which has no counterpart in unfrustrated systems. When there exists quenched randomess in addition to frustration, the ordering properties of such chiral system are expected to be quite novel. The purpose of the present study has been to investigate the phase transition of randomly frustrated systems with particular attention to the chirality by means of extensive Monte Carlo simulations. Two subjects, spin-glass magnets and ceramic superconductors, have been dealed with. By performing large-scale Monte Carlo simulations on the standard models for these systems, we have shown that a new chiral-glass phase, where the chirality orders in a spatially random manner with preserving the spin or the phase degrees of freedom disordered, is possible under appropriate conditions. Critical exponents characterizing the chiral-glass transition between the high-temperature disordered phase and the low-temperature chiral-glass phase are found to be close to the values of the three-dimensional Ising spin glass. In the case of spin-glass magnets, a new 'chirality' mechanism of the spin-glass transition has been proposed based on the numerical finding of the chiral-glass ordering, which could resolve the puzzle concerning the true nature of the experimentally observed spin-glass transitions. In the case of ceramic superconductors, it is shown that cuprate high-T_c superconductors, whose pairing symmetry has been established to be d-wave via recent experimental strudies, are good candidate materials to realize the chiral-glass state. Possible experimental detection of the proposed chiral-glass phase and the chiral-glass transition is examined in detail. In fact, several experimental results which partly support the chiral-glass state were already reported.