Molecular and Polymeric Magnets

Background

Traditional magnetic materials share the generic attributes of being atom-based (the active spins are located on atomic orbitals), having d- or f-orbital spin sites, and possessing extended network magnetic "bonding" in at least two dimensions. Furthermore, they are prepared by high-temperature metallurgical methodologies. Molecule-based organic/polymeric magnetic materials [1,2,3] are materials prepared through the established low-temperature synthetic procedure of organic, organometallic, and coordination metal synthetic chemistry, such that either one type of spins site is a molecular orbital made up of s and/or p atomic orbitals or the that molecular orbital is crucial in mediating the magnetic interaction.

Our group is interested in both basic and applied experimental studies of such molecule-based magnets. The basic research is oriented towards studies of the role of spin- and lattice-dimensionality, structural disorder and/or frustration on the magnetic ordering properties. The applied research is focused on low frequency applications of room temperature molecule-based magnets. The materials studied are quasi-one-dimensional, two-dimensional and three-dimensional compounds synthesized by chemists from the University of Utah and University of Tokyo. While the quasi one-dimensional systems provide an unusual opportunity for the study of spin- and/or lattice-dimensionality crossovers and of the mechanism of magnetic ordering, the room temperature magnets can open the field for a wide range of applications.

The collaboration with Dr. Miller's research group at University of Utah lead to the discovery of the first molecule-based magnet [Fe(C5Me5)2][TCNE] (Me = methyl, TCNE = tetracyanoethylene) [4], (due to the weak interchain interactions this system has low critical temperatures, of about 4.8 K) and of the first room temperature molecule-based magnet, V(TCNE)x y(solvent) [5] with a critical temperature estimated above 400 K. The recently started collaboration with Dr. Awaga's research group at University of Tokyo, has already lead to interesting results regarding geometrically frustrated systems.

Publications

J.S. Miller and A.J. Epstein, Designer Magnets - Recent Progress, Angewandte Chemie 106, 399-432 (1994) [International (English) edition 33, 385-415 (1994)].

J.S. Miller and A.J. Epstein, Designer Magnets,  Chemical & Engineering News 73 (40), 30-41 (1995).

J.S. Miller and A.J. Epstein, Molecular and Polymeric Magnets, Chemistry and Industry, 49-53 (1996).

J.S. Miller, A.J. Epstein, and W.M. Reiff, Molecular/Organic Ferromagnets, Science 240, 40-47 (1988).

J.M. Manriquez, G.T. Yee, R.S. McLean, A.J. Epstein, and J.S. Miller,  A Room Temperature Molecular/Organic-Based Magnet, Science 252, 1415-1417 (1991).

Created by Darren Gebler and Mihai Gîrtu. Maintained by John Rohrbacher. Last updated 6/1/00.