Resonance-assisted drastic transition in single-molecule magnets

Using exact diagonalization of the Hamiltonian and transition matrix in the energy eigenbasis, we perform model calculations of the magnetic relaxation rate in single-molecule magnets. A careful examination of the transition matrix reveals that resonant tunneling does not enhance transitions between the nearly degenerate states; rather, it suppresses them. Instead, transitions from one state in the degenerate pair to neighboring states of the other are significantly enhanced. We conduct a detailed analysis of the transition rates to clearly demonstrate how resonant tunneling modulates these processes. This work provides a substantial reinterpretation of the resonant magnetic relaxation in single-molecule magnets and clearly identifies the dominant relaxation pathways.