3. Fundamentals of condensed matter magnetism

3.1 The origin of condensed matter magnetism

The elementary magnetic moment of an atom results from two contributions from its incomplete electronic layers: the orbital moment, created by the rotation of electrons around the nucleus, in their orbits; and the spin moment, a purely quantum property of electrons. These two moments, coupled by an interaction of relativistic origin, the spin-orbit coupling, form the atomic elementary magnetic moment. The unit of moment is the Bohr magneton $\mu$ _B (= 9.274 0 × 10 ^{– 24} A · m ² ), which...