Unraveling Nanoscale Magnetization Dynamics: Slow Relaxing Single-Molecule Magnets

1. Understanding Nanoscale Magnetization DynamicsGregory S. Boebinger, Florida State University, DMR 0654118Electron Magnetic Resonance Facility (EMR) Magnetic molecules that exhibit slow relaxation upon removal from a polarizing magnetic field, referred to as single-molecule magnets (SMMs), are of considerable interest in terms of their potential use in molecular spin-based memory devices and quantum computers. Slow relaxation normally arises from an easy-axis magnetic anisotropy, so that SMMs preferentially orient their magnetic poles either ‘up’ or ‘down’ with respect to the easy-axis (see cover, right). Two separate EPR studies carried out in the DC field facility have identified slow relaxing SMMs in which the anisotropy favors confinement of the magnetic poles within a plane, rather like a freely rotating compass needle. Theoretical models were developed to account for the unexpected slow relaxation in both cases. Fundamentally new mechanisms appear to underpin these findings, suggesting new strategies for designing SMMs with improved characteristics. Citations: Slow Magnetic Relaxation Induced by a Large Transverse Zero-Field Splitting in a MnIIReIV(CN)2 Single-Chain Magnet, X. Feng et al., J. Am. Chem. Soc. 134, 7521–7529 (2012); Slow magnetic relaxation in a pseudotetrahedral cobalt(II) complex with easy-plane anisotropy, J. Zadrozny et al., Chem. Comm.48, 3927-3929 (2012) – featured on the cover of the journal (see above).