Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||TOKYO METROPOLITAN UNIVERSITY|
KOHGI Masahumi Tokyo Metropolitan Univ. Dept. Phys. Prof., 大学院・理学研究科, 教授 (30004451)
OCHIAI Akira Niigata Univ. Faculty of Technology Assoc. Prof., 工学部, 助教授 (90183772)
SATO Hideyuki Tokyo Metropolitan Univ. Dept.Phys.Prof., 大学院・理学研究科, 教授 (80106608)
SUZUKI Takashi Tsukuba Inst. Science & Technology Prof., 教授 (30004344)
MIGNOT Jean-Michel Laboratoire Leon Brillouin Research Director, LLB研究所, 主任研究員
IWASA Kazuaki Tokyo Metropolitan Univ. Dept.Phys. Assistant, 大学院・理学研究科, 助手 (00275009)
MIGNOT J.ーM. フランス, LLB研究所・CNRS, 主任研究員
MIGNOT J.ーM フランス, LLB研究所・CNRS, 主任研究員
|Project Period (FY)
1997 – 1998
Completed(Fiscal Year 1998)
|Budget Amount *help
¥10,800,000 (Direct Cost : ¥10,800,000)
Fiscal Year 1998 : ¥4,800,000 (Direct Cost : ¥4,800,000)
Fiscal Year 1997 : ¥6,000,000 (Direct Cost : ¥6,000,000)
|Keywords||charge ordering / heavy electron / valence fluctuation / Ce monopnictide / YbィイD24ィエD2AsィイD23ィエD2 / TmTe / low-carrier-system / neutron scattering / CeP / UNiGa / 磁気ポーラロン / 4重極秩序|
During 2 years of this project, total 13 domestic researchers were sent to institutions or international conferences in Poland, Czech, Germany and France to perform collaboration works and also to present the research results. Total 7 foreign researchers were also invited to perform the joint works related with the present project. The main results of the project are as follows :
(1) We have revealed, from the study of magnetic form factor of CeP by polarized neutron diffraction technique, that the unusual properties of CeP are due to the strong p-f mixing effect which pulls the ΓィイD28ィエD2-type crystal field excited state down below the ΓィイD27ィエD2-type crystal field ground state. It was also revealed that the CeAs exhibits quite similar magnetic phase diagram under high pressure above abou 0.3 GPa. In order to investigate the effect of the unusual magnetic properties to the crystal lattice of Ce-monopnictides we have measured the phonon excitations in CeSb by inelastic neutron scatterin
g, and found that a branch of unusual excitations is appears at the temperatures below Neel temperature.
(2) We have revealed, by neutron inelastic scattering, that the heavy electron anomalies of YbィイD24ィエD2AsィイD23ィエD2 a r ascribed to the spin excitations in the one-dimensional chains of YbィイD13ィエD1+ ions which is caused by the charge ordering. The charge ordering was confirmed to be rather perfect from the polarized neutron experiment. The inelastic neutron scattering studies under magnetic field revealed the opening of energy gap in the spin excitation spectra, which indicates the existence of a new correction term in the Heisenberg-type effective Hamiltonian of the charge ordered state of YbィイD24ィエD2AsィイD23ィエD2. The charge ordering phenomena of the similar material SmィイD24ィエD2BiィイD23ィエD2 was also observed by polarized neutron diffraction experiment.
(3) The quadrupolar ordering and diminishing process of the ferromagnetism under high pressure of TmTe were studied by neutron diffraction experiment.
(4) The heavy electron anomalies and valence fluctuation phenomena of SmィイD23ィエD2TeィイD24ィエD2 were studied by inelastic neutron and polarized neutron scattering.
(5) Strong magnetic anisotropy and metamagnetic properties of UNiGa and UCoAl and also the unusual properties of the skutterudite compound RfeィイD24ィエD2PィイD212ィエD2 were studied by macroscopic measurements such as the de Haas van Alphen measurement. Less