Magnetic and Quantum Properties of a New Class of Single-Molecule Magnets related to Magnetic Iron Oxides

University Of Florida, Gainesville FL

Investigators

Abstract

In this research funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor George Christou of the Department of Chemistry at the University of Florida is developing synthetic methods to very small (1-3 nm) iron oxide (Fe2O3) nanoparticles as molecular compounds of truly identical size and shape. Iron oxide nanoparticles are crucial to many magnetism-based technologies, including spintronics and quantum information systems, as well as applications in biomedical research, and better size- and shape-control are therefore of great importance. The research has employed molecular iron-oxide-carboxylate chemistry as a powerful route to 1-3 nm compounds having the same structure as the bulk iron oxides, bringing all the advantages of molecular chemistry to this area of ‘molecular nanoscience’, particularly single-size/shape, solubility, and crystallinity, allowing detailed study of their magnetic and quantum properties important to applications. Prof. Christou group is also involved in a wide range of state/national/international conference organization, education, and outreach activities at all levels, including K-12 students and under-represented minorities. Fe3+/O/carboxylate cluster chemistry provides a powerful ‘bottom-up’ route to 1-3 nm single-size/shape molecular fragments of the important magnetic iron(III) oxides, gamma-Fe2O3 and epsilon-Fe2O3. The clusters have the same Fe/O core structure as the metal oxides, and their molecular nature and crystallinity allow structural characterization to atomic resolution by single-crystal X-ray crystallography. They also exhibit the magnetic properties of gamma- and epsilon-Fe2O3, thus representing a new class of single-molecule magnets (SMMs), as well as the quantum properties (quantum tunneling of magnetization, quantum superposition and entanglement states, etc.) so important to new 21st century technologies such as spintronics and quantum information systems. In addition: (i) Fe3+/M2+ clusters are being targeted that are related to gamma-MFeO3 and MFe2O4 oxides (M = 3d or main group metal), such as the important magnetic CoFe2O4; and (ii) available clusters will be used as supports for magnetic 3d and/or 4f ions to assess the magnetic synergy between them, its correlation with the observed magnetic and quantum properties, and the detailed mode of binding to the cluster surface. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.