The Discovery and Properties of Room Temperature Molecule-Based Magents

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Date/Time:Monday, 17 Oct 2011 - Wednesday, 19 Oct 2011
Location:Physics Hall Room 5
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Gregory Girolami
University of Illinois

Prussian Blues, PBs, are chemical relatives of a pigment first discovered in the early 1700s, and have the general formula Mx[M'(CN)6]y•nH2O, where M and M' are transition metals. They adopt structures that can be considered as perovskite superlattices. Solids with the PB structure are especially attractive as candidates for new molecule-based magnets for several reasons: they can be prepared at room temperature from well-characterized and chemically stable building blocks, a wide range of metals with different spin states and oxidation states can be substituted into the structure, and the bridging cyanide ligands promote strong magnetic exchange couplings between the paramagnetic metal centers. These features allow considerable control over the nature and magnitude of the local magnetic exchange interactions. For example, PBs can be either ferromagnets or a ferrimagnets depending on the choice of metal center. The talk will describe the discovery of the first PB magnets that retain their magnetism at and above room temperature, and some of the remarkable physical properties, such as photo-induced magnetism, that PB magnets exhibit.