Transition Metal Clusters as Single-Molecule Magnets

University Of Florida, Gainesville FL

Investigators

Abstract

In this project funded by the Chemical Structure, Dynamics and Mechanisms B Program of the Chemistry Division, Professor George Christou of the Department of Chemistry at the University of Florida is seeking new molecular compounds that can function as nanoscale magnetic materials with properties relevant to new 21st century technologies such as quantum computers and spintronics. Molecular chemistry brings advantages such as solubility and crystallinity to this goal. It also provides methods for optimizing molecules for particular studies, such as characterizing the quantum physics properties important to these potential applications. The project's scope is broad spanning chemistry and physics. The project also provides new knowledge at the nanoscale that is not often available from traditional magnetic nanoparticles. The multi-disciplinary nature of the research also provides broad, high-level education and training for students, including underrepresented minorities. In addition, a number of outreach, education and international activities are carried out, including state and international conference organization and an annual Chemistry Day in the local community targeted at K-12 students. This research consists of two main objectives. The first one is to synthesize covalently-linked aggregates of two or more single-molecule magnets (SMMs) linked by dioximate or dicarboxylate bridges and to study their magnetic and quantum physics properties. Weak interactions between the SMMs leads to quantum superposition/entanglement states. These nebulous and fragile effects are detected and studied with techniques such as high-frequency electron paramagnetic (HFEPR) spectroscopy in the solid state. Extension of the HFEPR studies to frozen solutions is crucial to determine if structures and quantum effects remain unchanged on dissolution, providing a second phase for their study. The second objective is the preparation of molecules with a Mnx/O (x = 8-12) cage-like structures containing a heterometal M' of a different type (M' = Ca, La, Ln, Bi, Pb, etc.) at their center. The goal is to mimic in molecular compounds the repeating unit of certain mixed-metal oxides with the perovskite structure, particularly BiMnO3 and LnMnO3 (Ln = lanthanide) that are multiferroics, and thus to prepare molecules that function as 'molecular multiferroics', exhibiting both SMM and switchable electric polarization.