‘ๆ32‰๑ ŒดŒคE•บŒง‘ๅ‡“ฏƒRƒƒLƒEƒ€

“๚Žž: •ฝฌ19”N11ŒŽ5“๚(ŒŽ) 16F00`
Date and time: 5th Nov. (Mon.) 16:00`
๊Š: SPring-8, ŒดŽq—อ‹@\ 4ŠK‰žฺŽบ
Place: SPring-8, JAEA seminar room 4F
Title: What Can We Do Using Molecules?: Rational Design for Functional Materials
u‰‰Žา: ‹{โ“™ Ž (“Œ–k‘ๅŠw—Šw•”‰ปŠw)
Speaker: Prof. Hitoshi Miyasakai (Tohoku University)
Abstract:

i) Superparamagnetic Systems of Single-Molecule Magnets and Single-Chain Magnets: Anisotropic one-dimensional (1D) systems reveal various intriguing faces on their magnetization dynamics. Single-Chain Magnet (SCM) is a representative example [1], which exhibits Glauber dynamics dependent on intra-chain exchange couplings and their correlations. While Single-Molecule Magnet (SMM) behavior of [MnIII2(saltmen)2(ReO4)2] (saltmen2- = N,Nf-(1,1,2,2-tetramethylethylene) bis(salcylideneiminate)) is translated by its intrinsic characteristics [2], a similar dinuclear SMM, [MnIII2(salpn)2(H2O)2](ClO4)2 (salpn2- = N,Nf-(propane) bis(salicylideneiminate)), forming a 1D hydrogen-bonded organization presents dynamical behavior affected by a weak interaction via the hydrogen bonds (this compound can be regarded as an intermediate between SMM and SCM) [3]. A family of ferromagnetic regular chains with ST = 3, [MnIII2(saltmen)2NiII(pao)2(L1)2](A)2 (pao- = pyridine-2-aldoximate, L1 = monodentate N-ligands, A- = counter monoanions), is a typical SCM, dynamical behavior of which should be described as a function of only one kind of exchange coupling and its intra-chain correlation [4-6]. Meanwhile, an alternating ferromagnetic chain, [MnIII2(5-MeOsaltmen)2NiII(pao)2(bpy)](PF6)2, and its derivatives are a dimerized chain with J'1 >> J'2 ≈ 0, exhibiting quasi-SMM behavior explained by a double-spin flip mechanism. A similar alternating chain with different spin units (ST = 7/2), [MnIII2(5-MeOsaltmen)2CuII(pdao)2(tptz)](BPh4)2 (pdao2- = pyridine-2,6-dicarbaldehyde dioximate, tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine), finally reveals the double-spin flip SCM behavior.

ii) Nano-Dots Networks: The SMM particles assumable as gnano-dotsh possessing an artificial giant spin and strong anisotropy are specific building blocks for bulk materials. Coordination networks of 1D, 2D, and 3D using [Mn4] SMMs were synthesized and investigated their magnetic properties. The 1D chains are SCMs explained by Glauber dynamics [7,8]: namely, 1D arrangement of SMM is one way of rational design for SCMs. The 2D and 3D networks revealed a characteristic short-range/long-range dynamics affected by inter-molecular interactions and anisotropy of SMM units [9,10].

iii) The Rational Design for Ferromagnetic Semiconductors: How can we design a material for Spintronics devices? One way is to design ferromagnetic semiconductors, and nowadays, we know a few candidates based on hard inorganic materials. However, I suppose that metal coordination compounds (i.e., soft materials) enable to possess strong anisotropy and to design low-dimensional lattices are prefer for the materials. To design soft-materials ferromagnetic semiconductors, we proposed a way to construct gresonance scheme of electron-transferh in a coordination network [11,12].