| Project/Area Number |
11694110
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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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 | RIKEN, The Institute of Physical and Chemical Research |
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Principal Investigator |
KATSUMATA Koichi RIKEN, Magnetic Materials Laboratory, Chief Scientist, 磁性研究室, 主任研究員 (90002104)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAZAKI Hiroki RIKEN, Magnetic Materials Laboratory, Research Scientist, 磁性研究室, 研究員 (00271528)
TANAKA Yoshikazu RIKEN, Magnetic Materials Laboratory, Senior Research Scientist, 磁性研究室, 先任研究員 (90250109)
HAGIWARA Masayuki RIKEN, Magnetic Materials Laboratory, Senior Scientist, 磁性研究室, 副主任研究員 (10221491)
松田 雅昌 理化学研究所, 磁性研究室, 研究員 (90260190)
中村 哲也 理化学研究所, 磁性研究室, 基礎特別研究員 (70311355)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥13,800,000 (Direct Cost: ¥13,800,000)
Fiscal Year 2000: ¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1999: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | Quantum magnet / Quasi-one-dimensional antiferromagnet / Haldane effects / Spin-ladder / Field-induced phase transition / ESR / Magnetization process / Magnetic excitation |
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| Research Abstract |
In this project, we have performed several experimental studies on the spin, S=1 quasi-one-dimensional(Q1D) Heisenberg antiferromagnet Ni(C_5H_<14>N_2)_2N_3(PF_6)(abbreviated NDMAP) for which a field induced magnetic long range ordering (LRO)has been discovered by the present investigator and co-workers. From the temparature and magnetic field dependence of the magnetization, we got information on the spin arrangement in the ordered phase. Namely, at low temperature and high magnetic fields, spins are confined in the c plane and directed perpendicular to the external field. From electron spin resonance(ESR)measurements on NDMAP, we observed two kinds of signals at low temperature and high magnetic field, one of which corresponds to an antiferromagnetic resonance and the other to a one-dimensional excitation. This finding Provides a new knowledge towards the understanding of magnetic excitation in an S=1 Q1D antiferromagnet. We have also measured neutron scattering on deuterated single
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crystals of NDMAP and found a Bragg peak at(0, 1/2, 1/2)point associated with the long range magnetic ordering at high field and low temperature, thus confirming that the field unduced LRO really exists.
In collaboration with theoretical physicists, we have analyzed the magnetic field versus temperature phase diagram of NDMAP.We calculated the staggered susceptibility of S=1 one dimensional system with a single ion snisotropy taking into account the effects of the inter-chain couplings as the form of a mean-field. The theoretical result well reproduces the experimental phase diagram obtained by us.
We have measured the magnetic excitations from the ladder part of La_6Ca_8Cu_<24>O_<41> using a pulsed neutron source. We were successful in observing a full dispersion curve for the low energy excitation in the ladder. From the analysis of the data, we found that a four spin interaction with about 10% of the dominant interactions(leg and ladder) is necessary to get a reasonable result.
In addition to these, we have studied several quantum magnets and obtained new results, details of which are reported in the booklet. Less
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