Abstract
New {TbCu3} and {DyCu3} single-molecule magnets (SMMs) containing a low-symmetry Ln(III) center (shape measurements relative to a trigonal dodecahedron and biaugmented trigonal prism are 2.2-2.3) surrounded by three Cu(II) metalloligands are reported. SMM behavior is confirmed by frequency-dependent out-of-phase ac susceptibility signals and single-crystal temperature and sweep rate dependent hysteresis loops. The ferromagnetic exchange interactions between the central Ln(III) ion and the three Cu(II) ions could be accurately measured by inelastic neutron scattering (INS) spectroscopy and modeled effectively. The excitations observed by INS correspond to flipping of Cu(II) spins and appear at energies similar to the thermodynamic barrier for relaxation of the magnetization, ~15-20 K, and are thus at the origin of the SMM behavior. The magnetic quantum number M(tot) of the cluster ground state of {DyCu3} is an integer, whereas it is a half-integer for {TbCu3}, which explains their vastly different quantum tunneling of the magnetization behavior despite similar energy barriers.
Highlights
Single-molecule magnets (SMMs) display slow relaxation of the magnetization of purely molecular origin and have remained a hot topic because of their fundamental physics and potential applications.[1]
The main reason for these differences lies in the different ground states, Mtot being a halfinteger for {TbCu3} and Mtot an integer for {DyCu3}, and the associated more efficient ground state quantum tunneling of the magnetization (QTM) in {DyCu3}
This highlights how the often strong QTM associated with lanthanide ions can be modulated by using 3d−4f exchange interactions
Summary
Single-molecule magnets (SMMs) display slow relaxation of the magnetization of purely molecular origin and have remained a hot topic because of their fundamental physics and potential applications.[1] The majority of SMMs have been molecular 3d transition-metal complexes,[2] but in recent years, lanthanidecontaining molecules have gained prominence.3 3d−4f complexes are good candidates for SMMs: very large single-ion magnetic anisotropies have been observed for TbIII and DyIII,[4] and ferromagnetic coupling is commonly observed between CuII and ions such as GdIII, TbIII, and DyIII.[5] In comparison to polynuclear LnIII-based SMMs,[3,6] there are relatively few TbIIICuII SMMs, these using Schiff base or macrocyclic ligands, and even fewer DyIIICuII SMMs.[7] the origin of slow relaxation of the magnetization in 3d−4f SMMs needs more detailed investigation.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
