| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Research Abstract |
The purpose of this research project is to elucidate the essential nature of quadrupole interactions in which many researchers are interested in recently. One of the interested materials in this research area is CeB_6 that is investigated by us for long years. CeB_6 has only one 4f electron that is the origin of the quadrupode interactions. On the other hand, Tm has 13-4f electrons, then TmB_6 is counterpart to CeB_6 because 4f shell is full for 14 electrons. Therefore, the quadrupole nature of TmB_6 is very important research subject. However, TmB_6 is not found its phase in room temperature and in normal pressure. We found a method to break the bottleneck of this problem. In CeB_6, the Kondo-type singlet-ion nature is not changed by substitution of Ce by La. On the contrary, many new informations appeared in the investigations of Ce_xLa_<1-x>B_6 by the substitution. We succeeded to grow good quality of single crystals of Tm_xLa_<1-x>B_6, Tm_xYb_<1-x>B_6 by floating zone method. They shows phase transition at 7.5 K for Tm_xYb_<1-x>B_6 and at 4.5 K for Tm_xLa_<1-x>B_6 by the electrical resistivity and the magnetization measurements. It is hard to consider the magnetic order at these phase transitions because Tm is contained by only 25%. The phase transitions are thought to be attributed to quadrupole interactions. Therefore, many other measurements of specific heat, neutron scattering, etc. are needed now.
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