|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1992 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1991 : ¥1,500,000 (Direct Cost : ¥1,500,000)
As a two-years(1991-1992) project, the research of title "Study of the Physical Properties of Narrow and Direct f band" started. In 1991, we built up apparatus of specific-heat measurement by using the light-pulse method and then prepared single crystal to perform the study planned in 1992. On the other hand, within these two years, study of so-called f electron system make great progress, and it is now believed that the terminology "Valence Fluctuation" which reminds of dynamical properties is not appropriate expression not only for metallic but also for insulating valence fluctuation compounds. In other words, ground state of valence fluctuating regime which has been believed to belong to phenomena in narrow and direct f-band and was a main theme in this project can be fairly well described by normal band calculation. Needless to say, our studies on YbB_<12> and Ce_3(Au_<1-x>Pt_x)_3Sb_4 contribute much to this conclusion. On the basis of these background, new aspect of a question tha
t whether or not the anomalous ferromagnetic valence fluctuating compound CeRh_3B_2 and UIr_3B_2 can also be explained by the band calculation arises. The results of our research are as follows.
1) Valence fluctuating state of Ce_3(Au_<1-x>Pt_x)_3Sb_4... Pt substitution for Au decreases one electron, resulting in the shift of Ce valence from 3+ to 4+ and valence fluctuating state in Ce_3Pt_3Sb_4. In this process, semiconducting property persists. This implies that the energy gap arises from the band gap.
2) Transport of YbB_<12> under high pressure... We have measured pressure dependencies of the lattice parameter and energy gap. We have found that relative shift of lattice parameter at which energy gap becomes zero is the same in YbB_<12> and SmB_6.
3) Study of the giant crystalline field and ferromagnetism in CeRh_3B_2 via Soft-X-ray linear-dichroism.
4) Study of the magnetic property in Fe-doped UIr_3B_2... 5d band of Ir are polarized by Fe-moment and then ferromagnetism is appeared via f-d hybridization. Less