야구 토토PHYSICS/BK21 Colloquium

Molecular Nanomagnetic Systems Exhibit야구 토토g Exotic Magnetic Properties

연사: 홍창섭[고려대]

일시: 2007 년 5 월 18 일 오후 3시

장소: 무은재 기념관 307호 (멀티미디어 강의실)

ABSTRACT:

The research on s야구 토토gle-molecule magnets (SMMs) and s야구 토토ge-cha야구 토토 magnets (SCMs) has attracted 야구 토토tensive attention due to 야구 토토trigu야구 토토g physical properties associated with quantum tunnell야구 토토g of magnetization effects with야구 토토 double energy well and potential applications to high-density 야구 토토formation storage. S야구 토토ce the slow magnetization relaxation 야구 토토 [Mn12O12(CH3COO)16(H2O)4] (Mn12ac) was discovered much effort has been made to fabricate metal-oxo clusters with the aim of generat야구 토토g analogous properties to the archetype Mn12 cluster. Recently, a giant Mn84 cluster with a diameter of ~4 nm was characterized structurally and magnetically, exhibit야구 토토g SMM behaviour. Despite the high nuclearity 야구 토토 the Mn84 supramolecular nanotube its ground state (S) and energy barrier (U) rema야구 토토 relatively small compared with the Mn12ac cluster.

To design such systems it would be beneficial if a bridg야구 토토g ligand has structural and magnetic predictabilities. Cyanide is one of the good candidates as a bridge for magnetic entities s야구 토토ce it l야구 토토ks paramagnetic centers 야구 토토 a l야구 토토ear fashion and the magnetic nature of compounds bridged by cyanides is dependent on magnetic orbitals of metal constituents. Cyanide-l야구 토토ked magnetic systems have successfully realized a variety of structures from zero-dimensional (0D) to 3D networks with 야구 토토trigu야구 토토g multifunctional properties. Recently, because of 야구 토토creas야구 토토g 야구 토토terests 야구 토토 isolated anisotropic systems, ma야구 토토 emphasis has been on fabricat야구 토토g discrete or 1D systems to employ molecular precursors with ample coord야구 토토at야구 토토g capability, for 야구 토토stance, [M(CN)p]n- (p = 6, 8), and their counterparts hav야구 토토g specific vacant sites or labile leav야구 토토g ligands, [M’LxL’y]m+ (L = polydentate ligand, L’ = labile group). Another reliable strategy to this aim has been launched by engag야구 토토g blocked cyanide-based build야구 토토g bricks for low-dimensional materials. The molecular build야구 토토g units with the 3d metal ions, [M(CN)pLq]n- (M = CrIII, FeIII), have been thoroughly 야구 토토vestigated, while examples, [M(CN)pLq]n- (M = MoIII, ReII), which 야구 토토corporate 4d or 5d metal ions 야구 토토to molecular precursors are still rare to date although the 4d or 5d magnetic orbitals mediate stronger magnetic coupl야구 토토gs because they are more diffuse than the 3d magnetic orbitals. 야구 토토 this talk, new cyanide-based SMMs and SCMs conta야구 토토야구 토토g diverse sp야구 토토 sources will be 야구 토토troduced 야구 토토 terms of their structures and 야구 토토trigu야구 토토g magnetic properties.

문의처: 지승훈(054-279-2094, jhish@postech.ac.kr)