2001 Fiscal Year Final Research Report Summary
Study of Internal Field in the Magnetic Ordered Static of the rare-earth hexaboride by the Nuclear Magnetic Resonance
| Project/Area Number |
12640352
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
SERA Masafumi Hiroshima University, Graduate School of Advanced Science of Matter, Dept. of Quantum Matter, Prof., 大学院・先端物質科学研究科, 教授 (40196978)
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| Co-Investigator(Kenkyū-buntansha) |
KOJIMA Kenichi Hiroshima University, Faculty of Integrated Arts and Science, Associate Prof., 総合科学部, 助教授 (00100975)
IGA Fumitoshi Hiroshima University, Graduate School of Advanced Science of Matter, Dept. of Quantum Matter, Associate Prof., 大学院・先端物質科学研究科, 助教授 (60192473)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Orbital Order / Magnetic Order / Multipole / felectron / Kondo Effect / Nuclear Magnetic Resonance / Muon Spin Relaxation / Internal field |
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| Research Abstract |
CeB_6 is a famous compound showing a mysterious Antiferro-Quadrupolar(AFQ) ordering for 20 years. Very recently, the origin of the mysterious nature in the AFQ ordered state was revealed by Sakai et al. who introduced the AF octupolar (AFO) interaction. However, the microscopic mechanism has not yet been clarified. In order to clarify the unusual nature of the multipolar interaction in CeB_6, we have studied the magnetic, transport and thermal properties of Ce_xR_<1-x>B_6(R=Nd, Gd) system.
We found that the impurity Kondo effect exists at high temperatures in the electrical resistivity which is quite similar to that in Ce_xLa_<1-x>B_6. We also found that the Kondo effect continues to exist even in the long range AF magnetic ordered sate although the Ce ion contributes to the AF magnetic ordering. The ground state of the Ce ion in a small x region and for x>0.3 is the localized state but the Kondo singlet for 0.1<x<0.3. We expect that the present results promote the study of the Kondo ef
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fect in the long range AF magnetic ordering. The magnetic phase diagram of Ce_xNd_<1-x>B_6 was completed and found that phase II exists down to x=0.5 and disappears foe x<0.4. From these results, the AFQ interaction is suppressed rapidly with decreasing x below x=0.5, being different from the case of Ce_xLa_<1-x>B_6 where phase II continues to exist down to x〜0.3.
We studied the Ce_xGd_<1-x>B_6 system and found that the Gd doping suppresses the AFQ interaction but enhances the AFO one.
We analyzed the NMR results in phases II and III of CeB_6 and could succeeded to separate the contribution from the AF octupolar and AFQ moments. We also could observe the unusual magnetic field induced AF magnetic component, which we predicted by the mean field calculation for the 4 sublattice model. Through these studies, we could clarify the origin of the unusual properties in phases II and III as the result of the competition between three of the AFQ, AFO and AF exchange interactions.
We found that Yb_<1-x>La_xB_6 in a small x region exhibits the ferromagnetic ordering at T〜150K. This work will be the clue to clarify the origin of the ferromagnetic ordering in CaB_6 system. Less
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Research Products
(23 results)
