2007 Fiscal Year Final Research Report Summary
Study of the competition between the multipole interaction and Kondo effect in magnetic ion doped RB_6 (R=rare-earthion)
| Project/Area Number |
18540353
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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 |
Condensed matter physics II
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| Research Institution | Hiroshima University |
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Principal Investigator |
SERA Masafumi Hiroshima University, Graduate School of Advanced Sciences of Matter, Professor (40196978)
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| Co-Investigator(Kenkyū-buntansha) |
TOU Hideki Hiroshima University, Graduate School of Advanced Sciences of Matter, Associate Professor (60295467)
IGA Fumitoshi Hiroshima University, Graduate School of Advanced Sciences of Matter, Associate Professor (60192473)
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| Project Period (FY) |
2006 – 2007
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| Keywords | multipole order / octupole interaction / hidden order / Kondo effect / crystalline electric field / pressure effect |
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| Research Abstract |
The purposes of this study are to clarify the mechanisms of the competition between the multipole interaction and Kondo effect in RB_6(R=rare-earth ion). We obtained the following results.
(1) The investigation on Ce_xR_<1-x>B_6 showed that the Ce-Nd interaction is very weak but the Ce-Pr one is strong. In the latter, Ce and Pr ion cooperatively form the ordered state and Kondo effect is destroyed but in the former; the ordered state is constructed mainly by Ce ions and Nd ions have a strong paramagetnic character and Kondo effect remains even in the ordered state.
(2) By the neutron diffraction experiment on phase IV of Ce_<0.7>La_<0.3>B_6, the direct observation of the octupole order was discovered. However, as the O_<xy>-FQ order expected from the proposed octupole order competes with the O_<xy>-AFQ interaction which is the intrinsic interaction in CeB_6, the overall nature of Ce_xLa_<1-x>B_6 has not yet been clarified.
(3) From the investigation of the R-doping effect on phase IV of Ce_<0.7>La_<0.3>B_6, phase IV is found to be easily destroyed by a small amount of Nd and Pr dopings. However, in the case of Ce_<0.6>La_<0.4>B_6, phase IV is strong for the Nd-doping and the following unexpected results was obtained. The transition temperature from phase IV to paramagnetic one is enhanced by Nd doping.
(4) The pressure effect on PrB_6 was investigated. We discovered that a new phase appears above T_<10>=7K by applying only a small pressure of 0.3GPa. We also found that commensurate(C) phase is largely enhanced by applying pressure. These indicate that the short range interaction depending sensitively on the Pr-Pr distance.
(5) In the pressure effect on CeB_6 we discovered the appearance of the ferromagnetic(FM) order above P=1.3GPa. This FM ground state is constructed from the coexistence of the O_<xyz>-AFQ and T_<xyz>-AFO orders. To our knowledge, this is the first example of the FM ground state without the exchange interaction.
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