“…2,15–19 The higher the number of lanthanide ions, the less likely it is to have the same axis orientation; therefore, the SMMs containing only two lanthanide( iii ) ions are attracting more and more attention. 20–42 If a lanthanide( iii ) dinuclear SMM exhibits ferromagnetic interaction, the magnetic axis orientation of the two lanthanide( iii ) ions can be consistent, but this is a great challenging task; the reason is that the 4f electrons of different lanthanide( iii ) ions are not prone to magnetic exchange; even when the magnetic exchange occurs, it is usually a weak antiferromagnetic coupling. Notably, the ferromagnetic coupling between cations in lanthanide( iii ) SMMs may suppress the quantum tunnelling effect, which facilitates the presentation of SMM behavior in the zero field.…”