Tailoring Magnetic Properties in Transition Metal–Benzene Sandwich Clusters: Ways to Design Molecular Magnets

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Hongming Weng¹, Taisuke Ozaki¹, and Kiyoyuki Terakura¹^,²^,³

+ Affiliations

¹Research Center for Integrated Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1292²Creative Research Initiative “Sousei”, Hokkaido University, Sapporo 001-0021³Research Institute for Computational Sciences, Advanced Institute of Science and Technology, Tsukuba, Ibaraki 305-8568

Received February 20, 2008; Accepted April 2, 2008; Published May 26, 2008

Transition metal–benzene (TM _nBz _{n +1}, with TM=Sc, Ti, and V, n =1 and 2) multiple-decker sandwich clusters have been studied by first-principles calculations. It was shown in our previous paper that in V ₂Bz ₃, the antiferromagnetic (AFM) and ferromagnetic (FM) states are nearly degenerate since the energy gain in FM state due to Kanamori–Terakura mechanism is compensated by the energy gain in AFM state due to polarization of edge Bzs. To design new clusters having much more stable FM state, two approaches are suggested. One is reducing the number of d electrons and the other is to weaken the hybridization strength between transition metals and edge Bz. In order to demonstrate the latter aspect, we take a thought experiment of replacing edge Bz with cyclopentadienyl ring C ₅H ₅. Either of these two methods or combinations of both has been demonstrated to be effective. Thus, magnetic properties of transition metal–aromatic molecule sandwich clusters can be tailored.

https://doi.org/10.1143/JPSJ.77.064301

KEYWORDS: ferromagnetic cluster, benzene sandwiches, electronic and magnetic structureab initiocalculation, tight-binding model

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Tailoring Magnetic Properties in Transition Metal–Benzene Sandwich Clusters: Ways to Design Molecular Magnets

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