The Book Consists of Four Chapters

Chapter one describes the key physical properties of the electronic structure and the energy-level spectrum of the RE³⁺ both in the free-ion state and in two representative types of crystals (garnets and ortho-aluminates). These two crystalline hosts are currently the most sought after systems for modern practical applications. Discussion is developed in detail on the crystal electric field that removes the degeneracy of the RE³⁺ energy levels in the lattice and the magnetic features of these two RE³⁺-doped paramagnetic compounds having either Kramers or non-Kramers energy sublevels (Stark levels) depending on whether RE³⁺ is an odd-number or even-number electron system in the 4fⁿ sub-shell. Systematics of RE³⁺ garnets and ortho-aluminates are presented, with special attention paid to the description of the strongly anisotropic (“Ising”) character found in the magnetic behavior of some RE³⁺.

Chapter 2 is devoted to the optics of the 4f → 4f and 4f → 5d transitions in crystals. Current methods are used to calculate RE³⁺ transition energies and intensities of the forbidden 4f → 4f transitions in RE compounds. Results obtained from recently developed experimental methods used to measure the optical features of RE compounds (such as hot-band spectroscopy and site-selective polarized spectroscopy) are interpreted in detail by applying group theory to the analyses of the optical spectra of several RE ions in crystal field environments of low symmetry. Also, a theoretical description of the optical spectra associated with the allowed 4f → 5d transitions in the Tb³⁺ and Ce³⁺ garnets is analyzed within the framework of a “strong-weak” crystalline field approximation.

Chapter 3 is devoted to the phenomenological theory of magnetooptical phenomena that is general for all rare-earth dielectrics. A quantum-mechanical theory for the linear magnetooptical effects in paramagnetic RE garnets due to the allowed electric-dipole 4f → 5d transitions is considered in detail in the approximation of an “average” crystalline field. The theory of the Faraday effect is also applied to magnetic-dipole transitions in several RE³⁺. The role of the Van-Vleck contribution to the mixing of states in the circular magneto-optics of the Eu³⁺, Sm³⁺ and Gd³⁺ in the garnets is discussed in detail. The special features of the Faraday effect (FE) and magnetic circular dichroism (MCD) in YAG activated by the Tb³⁺ and Ce³⁺ are considered in the approximation of a “strong-weak” crystalline field within the ultraviolet spectral range. The nature of the magneto-optical activity (MOA) mechanism in the RE compounds with orthoaluminate structure is discussed using group theory as the tool for analysis. As a separate topic, the appearance of the so-called “Anti-Zeeman” effect is considered in the absorption spectra of terbium-gallium garnet TbGG in a magnetic field.

The final chapter covers the physics of the magnetooptical effects in radiative 4f → 4f transitions in RE compounds. Starting with the basic ideas concerning these effects, the authors present a set of experimental results for the degree of magnetic circular polarization luminescence (MCPL) of RE³⁺ in garnets, and they also analyze the features in the MCPL spectra in depth. The authors are the recognized authorities in this relatively new field of magneto-optics.

In the conclusive part authors give the reader an idea of the recent (2010 and 2011) technological activity derived from the results and predictions reported in the book and in other author publications.

The text of the book is well organized and clearly presented. In my opinion it will be of great use both for those who study the optical and magneto-optical properties of the RE compound professionally and for those who intend to obtain general ideas on these phenomena.

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