Elliptically polarized phonon mediation of long-range exchange coupling

Determine whether the experimentally observed long-range exchange interaction across insulating spacers thicker than 30 nm is mediated by elliptically polarized phonons, and establish the conditions under which such phonon-mediated coupling operates in these systems.

Background

The paper surveys experimental reports of long-range exchange interactions across insulating spacers exceeding 30 nm. These observations have prompted the proposal that elliptically polarized (chiral) phonons could mediate such coupling, but a definitive microscopic confirmation is lacking.

Motivated by this context, the authors develop a second-order perturbative framework for spin-spin interactions mediated by chiral phonons in two-dimensional insulators, deriving analytical forms for acoustic and optical phonons. Confirming the conjectured phononic mediation in the experimental systems would connect these theoretical results to observed phenomena.