Eigenstate versus Zeeman-based approaches to the solid effect: Eigenstate versus Zeeman-based approaches to the solid-effect

The solid effect mechanism for the dynamic nuclear polarization protocol was theoretically studied. In particular, we analyze the two most popular perturbation schemes to model the contact with the lattice at a given temperature: the Zeeman and the eigenstate-based approaches. A perturbation-based method is studied in order to compute transition rates between eigenstates in comparison to the Liouville time-evolution. We show that for weak hyperfine interactions the two approaches provide very similar results, while for strong hyperfine interactions the Zeeman approach is no longer reliable.