1992 Fiscal Year Final Research Report Summary
Anisotropic Hybridization in the Heavy-Electron Systems
| Project/Area Number |
03452044
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
FUJII Hironobu Fac. Integ. Arts. & Sci. Prof. Hiroshima Univ., 総合科学部, 教授 (30034573)
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| Co-Investigator(Kenkyū-buntansha) |
UMEO K Hiroshima Univ. Fac. Science, Res. Assoc., 理学部, 助手 (10223596)
SUZUKI T Hiroshima Univ. Fac. Science. Res. Assoc., 理学部, 助手 (00192617)
SAKURAI J Toyama Univ. Fac. Science, Prof., 理学部, 教授 (30033814)
FUJITA T Hiroshima Univ. Fac. Science, Prof., 理学部, 教授 (20004369)
TAKABATAKE T Hiroshima Univ. Fac. Integr. Arts. & Sci. Assoc. Prof., 総合科学部, 助教授 (40171540)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Hybridization / Kondo Lattice / Cerium Compound / Heavy Fermion / Valence Fluctuation / Metal-Insulator Transition / Single Crystal / Magnetism |
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| Research Abstract |
In the course of our searching study for new heavy-electron systems, we have found that several cerium and uranium intermetallic compounds display some interesting physical properties as Kondo-lattice groundstates, depending on the degree of hybridizations of f-electrons with the ligand s, p or d-electron states near the Fermi-level. Under consideration that such unusual physical properties should originate in anisotropic hybridization effects between the f and p or d-electrons, we planned to make single crystals of newly found systems and to perform their systematic investigations. The results obtained are summarized as follow: (1) An anisotropic gap in CeNiSn opens in the heavy-quasiparticle bands as temperature is reduced below 6K. The highly anisotropic behavior of susceptibility chi, electrical resistivity rho, thermoelectric power S and thermal expansion aipha reflects the strongly anisotropic hybridization of the Ce 4f-states with the Sn 5p- and Ni 3d-electron states in the epsi
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lon-TiNiSi orthorhombic structure. An anisotropic gap suppression is also observed under high-magnetic fields (H < 13T) along the a-axis and high pressures above 20 kbars. (2) For the heavy-fermions CePdIn and UPdIn with the same hexagonal ZrNiAl-type structure, chi and rho along the a and c-axes are significantly anisotropic and exhibit a marked contrast; chi_a*chi_c and rho_a>rho_c for CePdIn,and chi_a<<chi_c and rho_a<rho_c for UPdIn, respectively. For the comparison of the anisotropy in chi calculated by the bare CEF effects, the hybridization-induced anisotropy in CePdIn cancels in part the single-ion anisotropy of the CEF effects and vice versa in UPdIn. (3) The semiconducting to metal transition in UNiSn has been studied using highquality single phased samples prepared by annealing process at 800ﾟC for 90 days. The metallic state below 43K is stabilized by a type-I antiferromagnetic ordering of the U moments (like inverse Mott-transition). These phenomena could be explained by considering anisotropic hybridizaitons between U 5f-electron and Sn 5p-electron states. Less
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Research Products
(12 results)
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[Publications] T.Takabatake, M.Nagasawa, H.Fujii, G.Kido, M.Nohara, T.Suzkuki, T.Fujita, R.Helfrich, U.Ahlheim, K.Fraas, C.Geibel and F.Steglich: "Anisotropic Suppression of the Energy Gap in CeNiSn by High Magnetic Fields." Phys. Rev. B 45. 5470-5473 (1992)
Description
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