Susceptibility magneto-optic

The spin orientation order in the sample is created and monitored using standing wave optical pumping of the ground state hyperfine levels of the Tm" 2 ion (see Fig. 1). These levels have a magneto-optic susceptibility which depends on the electron spin orientation. The absorption constant for right or left circularly polarized light can be written as... 

Electro-optic and magneto-optic phenomena contain terms of nonlinear optics effects (see Eqs. (4.32), (4.33), (4.36), and (4.39)). On the other hand, acousto-optic effects which arise from a periodical density fluctuation of the medium, analogous to the Brillouin scattering phenomenon, do not contain terms of nonlinear optics, as a general rule.5) The perturbation of light propagation by sonic waves differs from that induced by electric and magnetic fields. As the electric susceptibility, xe, is a function of the density of the medium, it will be influenced by the periodical density fluctuation induced in a medium by sound waves. 

This susceptibility can be studied in the isotropic phase by electro-optical or magneto-optical techniques. Indeed, anisotropy of the electric and magnetic susceptibilities is proportional to the order parameter S, see Eq. 3.15. For example, nematic hquid crystal acquires an additional free energy — (l/2)XaH = in... 

The critical metallic components of advanced magnetic and magneto-optic (MO) storage devices— thin-film metal disks, inductive or magnetoresistive heads, and MO layers—are all susceptible to corrosion and each has been a subject of considerable study. Several review articles covering corrosion of magnetic-storage media may be found in the literature [135,136]. 

Reorientation of director L (or the optical axis) of the macroscopic volume of a liquid crystal under the effect of a field or flow of a liquid is Ae basis of most of the Imown electro- and magneto-optical effects. The anisotropy of the electrical and magnetic properties of the medium (dielectric constant Ae, diamagnetic susceptibility A%, electrical conductivity Aa) is the direct cause of orientation. The rearrangement processes are a function of the initial mientation of the molecules of the liquid crystal and its viscoelastic properties. The change in the c tical properties as a result of reorientation is the consequence of the optical anisotropy of liquid crystals. 

Electronic structures of GICs, thus theoretically characterized, are investigated experimentally by means of various techniques, such as x-ray photoemission spectra, ultraviolet photoelectron spectra, electron energy loss spectra, magneto-oscillation, optical reflectance, Raman spectra, Pauli paramagnetic susceptibility, electronic specific heat coefficient, NMR, positron annihilation, etc. Comparisons between theoretical treatments and experimental characterizations will be discussed in the Sections 6.3.2 and 6.3.3 of this chapter for actual GICs. 

Note The estimations are carried out using optical reflectance (< ), magneto-oscillation (m), spin susceptibility (s), and Raman scattering (r). 

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