| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
Through this three years project, it has been shown that the anomalous properties of high-T_c cuprates, such as spin-gap behaviors and spin-charge separation aspects, can be understood in a unified way by taking into account the effects of nested spin-fluctuations on the basis of the Fermi liquid theory. Namely, the origin of such anomalous behaviors has been shown to be attributed to the fact that the spectral weight of coherent spin fluctuations decreases in the low-energy regime because the Fermi surface of the quasiparticles is inevitably nested as the antiferromagnetic Mott insulating state is approached. At the same time, it has been pointed out that the incoherent part of spin fluctuations also plays a crucial role in order to understand these anomalous behaviors consistently.
It was also shown that the anomalous behaviors of V_2O_3, which had been considered to be a typical example exhibiting the Mott transition, can be understood as those originating from the nested spin-fluctu
… More
ations.
It was shown, on the basis of the Gutzwiller treatment of d-p model with reasonable values of parameters, that the high-T_c cuprates are the materials belonging to the intermediate coupling regime and their origin of Mott transition should be attributed to the antiferromagnetic correlations accompanied by the nesting of the Fermi surface.
A microsopic justification of the Itinerant-Localized Duality Model, which had been offering the basis of a theory of nested spin-fluctuations in strongly correlated metals, was given by means of the skeleton-expansion method of Luttinger-Ward.
The anomalous properties of weak magnetism of URu_2Si_2 was shown to be understood as a moment-induced mechanism of the crystal-field singlet ground state of f^2-configuration of U ion together with the nesting effect of a part of the Fermi surface. In particular, it was derived naturally that the magnetic-field dependence of T_N, the Neel temperature, and m (0), the ordered moment at T=0, are scaled by apparently different magnitudes of magnetic field. Less
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