2002 Fiscal Year Final Research Report Summary
Control of the Orbital Degrees of Freedem by the Magnetic Field and Pressure
| Project/Area Number |
11220206
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (B)
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Hiroshima University |
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Principal Investigator |
SERA Masafumi HIROSHIMA UNIV., ADV. MAT. SCI., PROFESSOR, 大学院・先端物質科学研究科, 教授 (40196978)
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| Co-Investigator(Kenkyū-buntansha) |
IGA Fumitoshi HIROOSHIMA UNIV., ADV. MAT. SCI., ASSOCIATE PROFESSOR, 大学院・先端物質科学研究科, 助教授 (60192473)
SUZUKI Takashi HIROSHIMA UNIV., ADV. MAT. SCI., PROFESSOR, 大学院・先端物質科学研究科, 教授 (00192617)
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| Project Period (FY) |
1999 – 2001
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| Keywords | ORBITAL ORDER / MAGNETIC ORDER / QUADRUPOLE MOMENT / OCTUPOLE MOMENT / KONDO EFFECT / fELECTRONS / dELECTRJONS / CONTROLE by EXTERNAL FIELDS |
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| Research Abstract |
This project has revealed the following new aspects on the orbital degrees of freedom in the 3d, 4f and 5f electron systems. We have shown that the origin of the unusual properties of CeB_6 showing thel antiferro-quadrupolar ordering at low temperatures and low magnetic fields is the coexistence and competition between the three interactions of the quadrupolar, octupolar and exchange. We have investigated the magnetic doping effect on the multipolar ordering in CeB_6 by using the Ce_xR_<1-x>B_6(R=Pr, Nd, Gd) systems and obtained the different affects between Pr and Nd ions with both spin and quadrupolar moments and Gd ion with only spin degrees of freedom. We have investigated the magnetic ion doping effect on the Kondo effect in CeB6 we found the extremely small interaction between Ce and Nd ions in Ce_xNd_<1-x>B_6 system. In order to clarify the origin of the weak ferromagnetism in Ca_<1-x>La_xB_6, we have investigated the Yb_<1-x>La_xB_6 system and found that this system exhibits the weak ferromagnetism at T_c=200K which is difficult to ascribe to the Fe impurity effect. As for the Kondo insulator system, we have investigated the Yb_<1-x>Lu_xB_<12> system and proposed the following model. Lu ion doping does not change the energy gay size of 200K but forms the in-gap state at the Fermi level and finally the usual Kondo effect becomes to be seen. As for the 3d electron system, we have investigated the Y_<1-x>Ca_xTiO_3 system. The origin of the metal-insulator transition at x=0.4 reported before has been ascribed to the phase separation between the insulating and metallic phases with different crystal structures. As for the 5f electron system, we have studied Ucu_2Sn exhibiting the long range order whose order parameter has not known by investigating the magnetoelastic properties and found that the ferro-quadrupolar order takes place.
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