How would you (in theory) manually store memories into a ferromagnetic material (cf Ising model)?

By "disguising" the memory-pattern with the energy signature of the naturally ordered state (eg uniform), from the perspective of the magnetic field.

"Recalling" the memory means lowering local temperature to the (critical) Curie point.

The "associative memories" to a ferromagnet X is anything that is *paramagnetic relative to* X.

Generalize to get Hopfield networks.