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Báo cáo hóa học: "Spin dynamics of an ultra-small nanoscale molecular magnet"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Spin dynamics of an ultra-small nanoscale molecular magnet | Nanoscale Res Lett 2007 2 168-174 DOI 10.1007 s11671-007-9049-5 NANO EXPRESS Spin dynamics of an ultra-small nanoscale molecular magnet Orion Ciftja Published online 6 March 2007 to the authors 2007 Abstract We present mathematical transformations which allow us to calculate the spin dynamics of an ultrasmall nanoscale molecular magnet consisting of a dimer system of classical high Heisenberg spins. We derive exact analytic expressions in integral form for the timedependent spin autocorrelation function and several other quantities. The properties of the time-dependent spin autocorrelation function in terms of various coupling parameters and temperature are discussed in detail. Keywords Spin dynamics Nanoscale molecular magnetism Time-dependent spin autocorrelation function Exchange interaction Biquadratic exchange interaction Pacs numbers 75.10.Hk 75.50.Xx Recent succesful efforts in synthesizing solid lattices of weakly coupled molecular clusters containing few strongly interacting spins has opened up the possibility of experimentally studying magnetism at the nano scale 1 . Due to the presence of organic ligands which wrap the molecular clusters the inter-cluster magnetic interaction is vanishingly small when compared to intra-cluster interactions therefore the properties of the bulk sample reflect the properties of independent individual nanoscale molecular clusters. The magnetic ions in each molecular cluster can The author wants to thank Dr. Gary Erickson for proof-reading the final draft of the paper. O. Ciftja H Department of Physics Prairie View A M University Prairie View TX 77446 USA e-mail ogciftja@pvamu.edu be generally arranged in different ways giving rise to structures of very high symmetry for example rings and or of lower symmetry presenting other important features. In some cases the positions of the magnetic ions in the cluster define a nearly planar ring structure within the host lattice for instance the Fe6 molecule is one of this type 2 . .