Slow Magnetic Relaxation in a Co~(II)-Y~(III) Single-Ion Magnet with Positive Axial Zero-Field Splitting

摘要

With the discovery of molecular complexes exhibiting slow relaxation of the magnetization and magnetic hysteresis at low temperature, research activity in the field of molecular magnetism based on coordination compounds has experienced spectacular growth. These nanomagnets, called single-molecule magnets (SMMs),straddle the quantum/ classical interface showing quantum effects, such as quantum tunneling of the magnetization and quantum phase interference, and have potential applications in molecular spintronics, ultra-high density magnetic information storage, and quantum computing at the molecular level. The motivation of much of this research activity has been provided by the prospect of integrating SMMs into nanosized devices. The origin of the SMM behavior is the existence of an energy barrier that prevents reversal of the molecular magnetization, although the currently observed energy barriers are (relatively) low and therefore SMMs act as magnets only at very low temperature. To increase the height of the energy barrier and therefore to improve the SMM properties, systems with large spin-ground states and/or with large magnetic anisotropy are required. The early examples of SMMs were clusters of transition metal ions, but recently mixed 3d/4f metal aggregates, low-nuclearity 4f metal complexes, and even mononuclear complexes (called single-ion magnets, SIMs) of lanthanide, actinide, and transition-metal ions have been reported to exhibit slow relaxation of the magnetization.