| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2004: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2003: ¥500,000 (Direct Cost: ¥500,000)
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| Research Abstract |
In this research project, we have theoretically studied a couple of quantum condensed matter systems which may include a kind of quantum intermediate state at low temperatures. The subjects we have chosen are in the following ;
1)Identifying theoretically the A-like phase of superfluid Helium-three in aerogel,
2)Examining a possibility of a quantum metallic phase (Bose-metal) in disordered granular superconductors,
3)Understanding effects of fluctuation on the phase transition between the normal and FFLO phases.
In 1),motivated by recent experimental facts on liquid Helium-three in aerogels, we have examined how the pairing symmetry and the superfluid long range order in the A-phase are affected by the random scattering events of quasiparticles provided by the aerogel. Through free energy calculations based on the conventional microscopic analysis, we have shown that, as far as the aerogel has no global anisotropy, the ABM pairing state of the bulk A-phase is unaffected by the aerogel, and
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that, as far as the disorder is weak enough, the resulting A-like phase is a superfluid-glass with quasi long-ranged superfluid order. These research results were reported in two papers published in the Physical Review.
In 2),inspired by a proposal that the resisitvity remains finite in a glass phase at zero temperature peculiar to the granular systems, we have examined a possibility of a quantum metallic phase in disordered granular superconductors. Our conclusion is negative on this respect : We find that the resistivity in the glass phase of granular systems is zero in agreement with the conventional wisdom on this issue. Due to this conclusion, no reliable theory favoring the presence of a quantum bole - metal phase is present.
In 3),an origin of the first - order transition behavior between the normal and the FFLO state in the heavy-fermion superconductor CeCoIn5 was discussed. We have shown on a firm evidence that the discontinuous nature of the normal to FFLO transition is of the mean-field character and not due to the critical fluctuation. Less
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