Optical Magnetic Excitations
Discussed in Chapters 3 and 4 are magnetic excitations in antiferromagnetic materials whose stoichiometric composition includes magnetic ions with un-filled 3d-shells. Both low-energy magnetic excitations (magnons) and high-energy ones (excitons) are investigated. Davydov magnetic splitting of light absorption lines, which is an experimental proof of the cooperative nature of optical excitations in these crystals, has been found to be particularly pronounced in a cubic antiferromagnetic RbMnF3 in a high magnetic field [201, 202]; this was also observed in more complex spectra without an external field [203, 204]. In this class of crystals optical transitions are mostly spin and parity forbidden. These excitations are imparted from one magnetic ion to another within a sublattice due to resonance exchange interaction. The excitation can be transmitted among ions with opposed orientation of spins due to antisymmetrical exchange interaction between a virtual magnon and an optical exciton.
KeywordsMigration Anisotropy Cobalt Manganese Fluoride
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