3. Solid magnets versus molecule magnets

3.1 Solid magnets

Solid magnets have magnetic properties linked to the ferromagnetic order present below their Curie temperature (T _c ). Molecule magnets, on the other hand, are finite, isolated molecules with magnetic properties of molecular rather than collective origin. To a first (and large) approximation, their properties are therefore confined to the size of the molecule formed. The main differences between bulk magnets and molecule magnets are detailed below.

When a massive, ferromagnetic magnet is subjected to a magnetic field, a large number of spins are correlated in magnetic domains (Weiss domains) separated by walls (Block walls in massive materials and Néel walls in thin films)