Phononic Resonant Relaxation in Magnetic Hysteresis of Single-Molecule Magnets

Lanthanide-based single-molecule magnets exhibit broad magnetic hysteresis, which manifests as slow magnetic relaxation in strong magnetic fields. However, the origin of the nontrivial hysteresis behaviors remains debated. Here, we propose two influential mechanisms: activation of optical-phonon-mediated direct transitions within the ground-state doublet and the resonant Raman process. These discoveries, coupled with the g-factor anisotropy, account for the observed hysteresis behaviors in the regimes of fast magnetic relaxation. Our findings complement the recognized mechanisms used to interpret the magnetic hysteresis of single-molecule magnets.