| Project/Area Number |
13640377
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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 | RIKEN (The Institute of Physical and Chemical Research |
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Principal Investigator |
HAGIWARA Masayuki RIKEN (The Institute of Physical and Chemical Research) Magnetic Materials Laboratory Senior Scientist, 磁性研究室, 副主任研究員 (10221491)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2001: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Geometrical frustration / Spin cluster / Quantum effect / Magnetic susceptibility / Magnetization / ESR / Magnetization plateau / Specific heat / クラスター / 磁化 |
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| Research Abstract |
We investigated a nickel four nuclear complex with a butterfly structure in which the nickel ions are located at the apexes of a diamond shape. Three different exchange interactions (J_1, J_2, J_3) exist in this compound. When these are antiferromagnetic, the system has a geometrical frustration.
We performed susceptibility and magnetization measurements on single crystals of this compound. The magnetization increases monotonically with increasing field and shows the 1/2 magnetization plateau. Then, the stepwise magnetization increases were observed around 40 T and 65 T. The magnitude of the magnetization plateau between 40 T and 65 T is three fourths of the saturation magnetization. The experimental results were analyzed by the above-mentioned model and evaluated the exchange constants. Moreover, we carried out the ESR experiments up to 55 T for the frequencies covering from 35 GHz to 1.6 THz. We observed ESR signals with g〜2.2 and g〜4.4 which correspond to the Δm=±1 and Δm=±2 transitions within Ithe lowest quintet, respectively.
In addition to this work, we performed specific heat experiments on an S=1 bond alternating chain and we observed a sharp peak attributed to the long range ordering when the energy gap closes by application of magnetic fields. We have found the temperature dependence of the peak is very close to that of the Haldane material NDMAP.
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