Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet.

Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation [(Cp i Pr5 )Dy(Cp*)]+ (Cp i Pr5 = penta-iso-propylcyclopentadienyl, Cp * = pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of U eff = 1,541 cm-1 is also measured. The magnetic blocking temperature of T B = 80 K for this cation overcomes an essential barrier towards the development of nanomagnet devices that function at practical temperatures.