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We report here a linear fluoride-bridged Double-Decker Dysprosium metallacrown with high-performance SMM. The successful introduction of stronger magnetic exchange-coupling in the axial direction, which is collinear with the Ising-type magnetic anisotropy axis of dysprosium ions, plays a pivotal role in improving the SMM properties of the double-decker Dysprosium metallacrown.

Single-molecule magnets (SMMs) are promising elements for quantum informatics. In the presence of strong magnetic anisotropy, they exhibit magnetization blocking - a magnetic memory effect at the level of a single molecule. Recent studies have shown that the SMM performance scales with the height of magnetization blocking barrier. By employing molecular engineering this can be significantly modified, remaining independent from other external factors such as magnetic field. Taking advantage of hyperfine coupling of electronic and nuclear spins further enhances their functionality, however, a poor understanding of relaxation mechanisms in such SMMs limits the exploitation of nuclear-spin molecular qubits. Here we report the opening discovery of field-dependent oscillation of the magnetization blocking barrier in a new holmium metallacrown magnet driven by the switch of relaxation mechanisms involving hyperfine interaction. Single-crystal magnetic hysteresis measurements combined with first-principles calculations reveal an activated temperature dependence of magnetic relaxation dominated either by incoherent quantum tunneling of magnetization at anti-crossing points of exchange-hyperfine states or by Orbach-like processes at crossing points. We demonstrate that these relaxation mechanisms can be consecutively switched on and off by increasing the external field, which paves a way for manipulating the magnetization dynamics of SMMs using hyperfine interaction., 6 pages, 4 figures

In 2016, we reported a single-ion magnet [Dy(bbpen)Br] with an energy barrier over 1000 K. Here a dimeric [Dy2(mu-CO3)(bbpen)2(H2O)].H2O.CH3OH (1) and a trimeric [Dy3(mu3-CO3)(bppen)3](CF3SO3).H2O (2) single-molecule magnets (SMMs) were obtained through replacing the Br- anion with the carbonate bridge. Their effective relaxation barriers at zero dc field are decrease to 51 K and 422 K, respectively, which are consist with their structural modifications.