Magneto-Optics and Spectroscopy of Antiferromagnets

1 Magneto-Optic Effects in Non-Centroantisymmetrical Antiferromagnetic Crystals.- 1.1. Symmetry of the Optical Properties of Magnetically Ordered Crystals.- 1.2. Symmetry of the Linear Magneto-Optic Effect (LMOE).- 1.3. Light Polarization Transformation at Magneto-Optic Effects, and Specific Features of Experimental Method.- 1.4. Experimental Investigations of the Linear Magneto-Optic Effect.- 1.4.1. The Linear Magneto-Optic Effect in Cobalt Carbonate.- 1.4.2. Reduction of the Optical Class of Tetragonal Antiferromagnetic Cobalt Fluoride in a Longitudinal Magnetic Field.- 1.4.3. Orthorhombic Noncollinear (Canted) Antiferromagnetic DyFeO3.- 1.4.4. The Linear Magneto-Optic Effect in Other Antiferromagnetic Crystals.- 1.5. Magnetic Gyrotropy Quadratically Dependent on Magnetic Field Strength.- 2 Magneto-Optical Methods for Investigating the Structure of Antiferromagnetically Ordered Crystals.- 2.1. Visualization of Collinear or 180-Degree Antiferromagnetic Domains.- 2.1.1. Antiferromagnetic Domains in a Tetragonal Cobalt Fluoride.- 2.1.2. The Magnetic Phase Transition in Cobalt Fluoride Induced by a Magnetic Field H ? C4.- 2.2. Magnetic Structure of the Antiferromagnetic Calcium—Manganese—Germanium (CaMnGe) Garnet.- 2.2.1. The Magnetic Point Symmetry of Manganese—Germanium Garnet.- 2.2.2. Magneto-Optical Observation of Crystalline Twins.- 2.3. The Antiferromagnetic Domains and Two-Phase Magnetic Structures in DyFeO3.- 2.3.1. Antiferromagnetic Domains.- 2.3.2. The Incoherent Two-Phase Domain Structure.- 2.3.3. Coherent Two-Phase Domain Structures.- 3 Optical Magnetic Excitations.- 3.1. The Exciton Description of Magnetic Excitations.- 3.2. The Mechanism of Magnetic Excitation Generation by Light.- 3.2.1. One-Particle Processes (Magnetic Dipole Absorption and Emission).- 3.2.2. Multiparticle Processes (Electric Dipole Absorption and Emission).- 3.2.3. Bonded States.- 3.2.4. Parametric Excitation by Optical Pumping.- 3.2.5. An Estimate of Some Parameters of Optical Excitations.- 3.3. Multiquantum Excitation of Two-Particle Transitions.- 3.3.1. Multiquantum Absorption of Light.- 3.3.2. Two-Exciton Absorption of Light in the Case of Four-Quantum Excitation.- 3.3.3. Influence of Statistical Properties of Light on Two-Exciton Four-Photon Absorption.- 3.4. Dynamics of Magnetic Excitons.- 3.4.1. Transfer of Electron Excitation Energy.- 3.4.2. Character of Exciton Motion.- 3.4.3. Coherent Excitons.- 3.4.4. Noncoherent Magnetic Excitons.- 3.4.5. Change of Exciton Mobility at Inducing Intersublattice Transitions.- 3.5. Radiation Decay of Magnetic Excitons.- 3.5.1. The Increase of Exciton—Magnon Luminescence in a Magnetic Field.- 3.5.2. Enhancement of Exciton Radiation Transition.- 3.5.3. Biexciton Annihilation.- 4 Magnetic Excitons as a Method of Study of the Magnetic Properties of Antiferromagnets.- 4.1. Spectroscopic Studies of Spin Waves.- 4.1.1. Three-Dimensional Magnetic Crystals. Energy of Magnons at the Boundary of the Brillouin Zone.- 4.1.2. Low-Dimensional Magnetic Crystals. Magnon Energies Inside the Brillouin Zone.- 4.1.3. Impurity Modes.- 4.2. Magnetic Excitons as an Instrument to Investigate the Magnetic Configurations of Antiferromagnets.- 4.2.1. Equilibrium Structures.- 4.2.2. Phase Transitions in an Antiferromagnet with Anisotropy of “Easy-Axis” Type.- 4.3. Photoinduced Magnetic Effects.- 4.3.1. ErCrO3. Spin-Reorientation Phase Transitions.- 4.3.2. EuCrO3. Origin of a New Magnetically Ordered Phase.- 4.3.3. MnF2. Photoinduced Single-Ion Magnetic Anisotropy.- 5 Delocalization of Impurity Excitations in Antiferromagnetic Insulators.- 5.1. Localized States (Single-Impurity Approximation).- 5.1.1. Theory.- 5.1.2. Experimental Data and Their Interpretation.- 5.2. Localization and Delocalization States in the Anderson and Lifshitz Models.- 5.2.1. The Anderson Model.- 5.2.2. The Lifshitz Model.- 5.3. Coherent and Incoherent Impurity Excitations. Impuritons.- 5.3.1. Electron Excitations in the Presence of Large-Radius Impurity States. Theory.- 5.3.2. Rearrangement of the Spectrum of Spin Excitations in an Antiferromagnet with Magnetic Impurities in an External Magnetic Field. Magnetic Impuritons.- 5.3.3. Experimental Studies of Magnetic Impuritons (CoF2 + c Mn).- 5.3.4. Orthogonal- and Collinear-Type Impurities in CoCO3 + Fe + Mn + Ni.- 5.3.5. Magnetic Impuritons Near the Top of a Magnon Band (FeF2 + Co).- References.