Reconsidering spin-phonon relaxation in magnetic molecules

Because of the larger intra-molecular distortion, optical phonons usually have stronger spin-phonon coupling than acoustic phonons in molecular magnets. This property may pose problems to the theory of spin relaxation in ordinary paramagnetic materials, which have served as the basis for the understanding of spin dynamics in molecular magnets for decades. In this review, we explain why the Raman processes driven by optical phonons can play a dominant role at low temperature and provide unconventional dependence between relaxation time and temperature. Especially, we emphasize that the sub-barrier relaxation and anomalously low Raman exponents are two common signatures of the dominance. We also present the algorithm and implementation for calculating spin-phonon relaxation in molecular solids with density functional theory codes.

Automated summary

In this review, the importance of Raman processes driven by optical phonons in spin relaxation theory in molecular magnets is explained. The sub-barrier relaxation and anomalously low Raman exponents are emphasized as common signatures of this dominance.