| Project/Area Number |
14540533
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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 |
機能・物性・材料
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| Research Institution | Osaka University |
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Principal Investigator |
NAKANO Motohiro Osaka University, Graduate School of Engineering, Lecturer, 大学院・工学研究科, 講師 (00212093)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2002: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | single-molecule magnet / polynuclear complex / magnetic susceptibility / magnetic anisotropy / non-collinear magnetism / Spin-crossover complex / dielectric constant / Jahn-Teller effect |
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| Research Abstract |
1.Relaxation Mechanism of Single-Chain Magnets
Single-Chain Magnets (SCMs) are a class of quantum magnets, recently developed from Single-Molecule Magnets (SMMs). We proposed a novel mechanism of relaxation processes in SCMs based on a spin-vector model characterized by an intrachain ferromagnetic interaction J along with a single-ion anisotropy D. This model can be applied to a wide range of SCM systems from a SMM limit J/D 0 of isolated molecule to a Glauber-dynamics limit J/D >> 1 for a pure Ising chain. It is an excellent feature of the model that it provides a rational account for a "barrier-height crossover" observed in some ferromagnetic SCMs as a crossover of dominant relaxation process from a single-spin flip to a two-spin cluster flip possessing different activation barriers.
2.Critical Phenomena of Spin-Crossover Complex [Mn(taa)]
Spin-crossover complex [Mn(taa)] is known as a unique system showing a dielectric response in addition to an optically-controllable spin bistability. In order to clarify intermolecular interactions responsible to the phase transition in [Mn(taa)] crystals, we prepared some mixed-crystals with [Ga(taa)], a diamagnetic analogue of the Mn complex with the isomorphous crystal structure. A T-x phase diagram of [Mn_xGa_<1-x>(taa)] determined by magnetic and dielectric measurements revealed a critical phenomenon switching from a first-order phase transition to a spin-equilibrium behavior. The suppression of the spin-crossover phase transition made it possible to estimate the energy barrier for pseudo-rotation of an [Mn(taa)] molecule.
3.Development of Computer Programs for Magnetization Analysis
Some computer codes were developed to analyze magnetization curves and HF-EPR results of SMMs. Among them a code implementing the ligand-field theoretical approach was especially effective to elucidate magnetic properties of SMMs including Co(II) ions, which were difficult to be treated by conventional spin-Hamiltonian approach.
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