There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

3d-transition-metal-doped ZnO films (n-type Zn1−xMxO (x=005–025): M=Co, Mn, Cr, Ni) are formed on sapphire substrates using a pulsed-laser deposition technique, and their magnetic and electric properties are examined The Co-doped ZnO films showed the maximum solubility limit Some of the Co-doped ZnO films exhibit ferromagnetic behaviors with the Curie temperature higher than room temperature The magnetic properties of Co-doped ZnO films depend on the concentration of Co ions and carriers

Magnetic and electric properties of transition-metal-doped ZnO films

Recent advances in the theory and experimental realization of ferromagnetic semiconductors give hope that a new generation of microelectronic devices based on the spin degree of freedom of the electron can be developed. This review focuses primarily on promising candidate materials (such as GaN, GaP and ZnO) in which there is already a technology base and a fairly good understanding of the basic electrical and optical properties. The introduction of Mn into these and other materials under the right conditions is found to produce ferromagnetism near or above room temperature. There are a number of other potential dopant ions that could be employed (such as Fe, Ni, Co, Cr) as suggested by theory [see, for example, Sato and Katayama-Yoshida, Jpn. J. Appl. Phys., Part 2 39, L555 (2000)]. Growth of these ferromagnetic materials by thin film techniques, such as molecular beam epitaxy or pulsed laser deposition, provides excellent control of the dopant concentration and the ability to grow single-phase layers. T...

/pdf/wide-band-gap-ferromagnetic-semiconductors-and-oxides-48l1gtt253.pdf

Wide band gap ferromagnetic semiconductors and oxides

Microwave quality factor measurements for pure and mixed stages of graphite ferric chloride intercalation compounds have been carried out at X-band microwave frequency of 9.1582 GHz. The change in quality factor and hence the loss confirms the metallic nature of the graphite ferric chloride intercalation compounds that were studied.

Microwave studies on some low stage graphite ferric chloride intercalation compound

Dielectric characterization studies of hydrogen-bonded polar liquids in nonpolar medium using cavity perturbation technique

The effect of substitution of Sr at the A site of Ba(Zn1/3Ta2/3)O3 was investigated with respect to tolerance factor (t) which determines the degree of packing of A and B site ions of perovskite unit cell, with an intension to understand the correlation between the temperature dependent dielectric properties with structure. The investigation reveals that the Ba rich compositions with highly symmetric cubic phase exhibits negative variation of dielectric constant with temperature and the Sr rich compositions with distorted structure always show positive variation of dielectric constant with temperature. The profile of τe variation of all the compositions was scaled with respect of reduced temperature which exhibits an exact signature of τe variation with the compositions at room temperature. The observed mechanism was explained using Clausius Mossoti equation.

https://iopscience.iop.org/article/10.1143/JJAP.50.021501/pdf

Correlation Between Tolerance Factor and Temperature Coefficient of Dielectric Constant of (Ba,Sr)(Zn1/3Ta2/3)O3 Dielectric Resonator

Bond and molecular polarizabilities of cytosine and a few of its substituents are determined by force field technique and /spl delta/-function potential model. Interestingly, the longitudinal bond polarizability coefficients of C/sub 4/-C/sub 5/, C/sub 5/-CH/sub 3/ bring out the aromatic nature of the C/sub 5/ X-ray and NMR observations, quantum chemical calculations and UV photoelectron studies are discussed in relation to this. The agreement is satisfactory.

http://ieeexplore.ieee.org/iel3/3804/11132/00532983.pdf

Bond and molecular polarizabilities in the structural studies of cytosine and its substituents

Measurements of the anisotropy fields were performed on "as grown" Bi-TmFeGa Garnet, Bi-YIG and commercial 2 µm bubble film with compositions that were grown on [111] GGG substrates. Results from three independent measurement techniques of the anisotropy field are compared and reported. These techniques are the dynamic susceptibility (MO), ferromagnetic resonance (FMR) and visual (V) observation of the domain pattern in a changing inplane field. The three measurements give results to agree within 5–10% of each other neglecting the cubic anisotropy energy's contribution. The advantages and limitations of each technique for routine characterization of the magnetic films are discussed.

V. R. K. Murthy

Papers

Microwave studies on some low stage graphite ferric chloride intercalation compound

Dielectric characterization studies of hydrogen-bonded polar liquids in nonpolar medium using cavity perturbation technique

Correlation Between Tolerance Factor and Temperature Coefficient of Dielectric Constant of (Ba,Sr)(Zn1/3Ta2/3)O3 Dielectric Resonator

Bond and molecular polarizabilities in the structural studies of cytosine and its substituents

Comparative Study of Anisotropy Fields in Garnet Films