Magnetooptical Activity of Allowed Electron Transitions in Atoms in Free State and in Crystals

Magnetic circular birefringence (MCB) is rigorously decomposed into diamagnetic (A) and paramagnetic (B and C) terms without substantial restrictions on the values of the fields and interactions. Peculiarities of the magnetooptical properties of the 3d‐and 4f‐atoms both, in free state and in crystals are analyzed on the basis of most general properties of the atom wave functions, spin‐orbit interaction and interactions of the atom with the magnetic and crystal fields, and the values of MCB terms are evaluated. The crystal field is shown to be in all cases a condition necessary for the B‐terms (mixing term) to exist. The mechanisms of the B‐term occurrance are considered and its values at different mechanisms are evaluated. MCB due to magnetic ordering is considered.