Equal-interval splitting of quantum tunneling in single-molecule magnets with identical exchange coupling

The equal-interval splitting of quantum tunneling observed in simple-Ising-model systems of Ni-4 (3D) and Mn-3 (2D) single-molecule magnets (SMMs) is reported. The splitting is due to the identical exchange coupling in the SMMs, and is simply determined by the difference between the two numbers of the spin-down n(down arrow) and spin-up n(up arrow) molecules neighboring to the tunneling molecule. The splitting may be presented as (n(down arrow) - n(up arrow)) JS/g mu(0)mu(B), and the number of the splittings follows n + 1 where n = n(down arrow) + n(up arrow) is the coordination number. Besides, since the quantum tunneling is heavily dependent on local spin environment, the manipulation of quantum tunneling may become feasible for this kind of system, which may shed light on applications of SMMs.