1986 Fiscal Year Final Research Report Summary
Systematic Study of Dense Kondo Materials
| Project/Area Number |
59060001
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
KASUYA Tadao Faculty of Science, Tohoku University, 理学部, 教授 (30004245)
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| Co-Investigator(Kenkyū-buntansha) |
DATE Muneyuki Faculty of Science, Osaka University, 理学部, 教授 (80028076)
ISHIKAWA Yoshikazu Faculty of Science, Tohoku University, 理学部, 教授 (10013468)
ENDOH Yasuo Faculty of Science, Tohoku University, 理学部, 教授 (00013483)
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| Project Period (FY) |
1984 – 1986
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| Keywords | Rare earth compounds / Kondo effect / Dense Kondo state / Heavy Fermion / Crystal growth / Dilution refrigerator |
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| Research Abstract |
The present research project was aimed to investigate the dense Kondo problem. The project includes the single crystal growth of typical Kondo materials with high quality, the magnetic studies under high magnetic field and the neutron scattering at very low temperatures well below 1K. Several new methods to grow single crystals such as the hot isostatic processing furnace, ultra high presure furnace and tri-arc furnace were developed. The high field up to 37T Tesla was achieved with the long duration. Neutron scattering was performed at about 6 Tesla and 100 milli K.
During these three years new heavy fermion materials were found and investigated these novel features, namely CePtSi,Ce <Cu_2> In and so forth. Particularly Ce <Cu_2> In was appreciated to be the first cubic heavy Fermion compound. Yb <B_(12)> and Ce <Cu_x> <Pd_(3-x)> were also found to be the gap type mixed valence compounds such as Sm <B_6> . Other new materials besides Ce compounds were found to show the dense Kondo behavior, which are <Yb_4> <As_3> , <Sm_4> <As_3> ,Sm <Sn_3> and so forth.
Following important results were obtained: The cross-over phenomena from magnon excitations to those of heavy fermions was observed for the first time for the magnetic Kondo systems. The unusual magnetic behaviors of Ce <Rh_3> <B_2> were fully understood by the both detailed experiments using single crystals and theoretical investigation with the direct f-f band model. A peculiar relaxation time behavior was observed by NMR in various uranium compounds, UP, U <Al_2> , U <Cu_5> and U <Be_(13)> .
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