Significant Control on Zero-Field Quantum Tunneling of Magnetization in Dysprosium Based Single-Molecule Magnets via Orientation of the Anilato Ligand

Abstract

Tuning the bridging fashion of anilato ligand in dinuclear Dy^III complexes, reveals a sizable effect on the slow relaxation of magnetization. Combined experimental and theoretical studies divulge that the geometry with high order axial symmetry (pseudo square antiprism) reduces the transverse crystal fields corresponding to QTM (quantum tunneling of magnetization) resulting in a significant increase in energy barrier (U_eff =518 cm^-1 ) through the Orbach relaxation process whereas the geometry with lower symmetry (triangular dodecahedron, pseudo D_2d ) enhances the transverse crystal fields that accelerate the ground state QTM process. Notably, the value 518 cm^-1 represents the highest energy barrier among anilato ligand based SMMs.

Keywords: QTM; axial symmetry; dinuclear dysprosium complex; redox active bridging ligand; single molecule magnet.