$mathcal{PT}$ symmetric quantum mechanics from dynamically coupled macrospins

We investigate the dynamical hybridization of classical spin precession modes. We consider a broad class of low-frequency purely dynamical interactions respecting Onsager reciprocity which may macrosopically break time reversal symmetry at the level of the Landau-Lifshitz-Gilbert equation. We establish a correspondence to non-Hermitian quantum mechanics, and show that in the case of dissipative coupling we generically predict spontaneous $mathcal{PT}$ symmetry breaking in the analogue quantum system, allowing us to address formally the phenomenon of level attraction in magnetic heterostructures. Furthermore, we make connections to true quantum mechanics by rederiving our interactions from a microscopic model.