2001 Fiscal Year Final Research Report Summary
Quantum Critical Phenomena in Heavy-Fermion System under Pressures
| Project/Area Number |
11440111
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
TAKABATAKE Toshiro Hiroshima University, Grad. School of Advanced Sciences of Matter, Prof., 大学院・先端物資科学研究科, 教授 (40171540)
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| Co-Investigator(Kenkyū-buntansha) |
IGA Fumitoshi Hiroshima University, Grad. School of Advanced Sciences of Matter, Assoc. Prof., 大学院・先端物資科学研究科, 助教授 (60192473)
UMEO Kazunori Hiroshima University, Grad. School of Advanced Sciences of Matter, Res. Assoc., 大学院・先端物資科学研究科, 助手 (10223596)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Pressure / Quantum Critical Phenomena / Heavy Fermion System / Spin Fluctuation / Antiferromagnetism / Single Crystal / Uniaxial Pressure / Crystal Field |
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| Research Abstract |
We studied the quantum critical phenomena of heavy fermion systems under pressures by means of high-quality single crystals. New findings are as followings.
1. Hexagonal heavy fermion system Ce_7Ni_3 : Ce_7Ni_3 undergoes tow antiferromagnetic transitions at 1.8 K and 0.7 K. The antiferromagnetic order vanishes at B//c = 0.3 T. For B//c > 0.6 T, a new magnetic ordered phase appears below 0.5 K. For 0.3 T < B//c < 0.6 T, the specific heat C follows the form of C/T∝-lnT, so called non-Fermi-liquid behavior. The origin of the field-induced magnetic phase may be attributed to a geometrical frustration in the magnetic moment of Ce sites formed a quasi-regular tetrahedron
2 Uniaxial-pressure induced magnetic order in CeNiSn : CeNiSn is a paramagnetic semimetal with a pseudo-gap. By applying the uniaxial pressure of 0.13 GPa along the c axis, an antiferromagnetic order appears at around 3 K. For P//a, however, the density of carriers increases. The Kondo temperature for the crystal field ground state estimated by the resistivity for P//c is suppressed with pressure. Therefore, we may deduce that the formation of magnetic order is attributed to the weakened hybridization in a-b plane between the 4f electrons for the crystal field ground state and conduction electrons.
3 Non Fermi liquid behavior in Ce_2Rh_3Ge_5 under pressures : The critical pressure Pc where the antiferromagnetic order of orthorhombic Ce_2Rh_3Ge_5 with T_N = 4.9 vanishes was estimated to be 0.45 GPa. Even for P>3Pc, non-Fermi-liquid behavior is observed in both the resistivity ρ and the susceptibility χ : ρ ∝T^<1.45> and χ ∝1-T^<0.27>. Because the magnetization hardly decreases for P = 3Pc, the origin of the non-Fermi-liquid behavior may be due to a short-rang magnetic order of the remaining local moments.
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