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

An automated ferroelectric hysteresis loop tracer, developed using an INTEL 8085 microprocessor is described. This setup can be used to study the growth of a hysteresis curve at any desired temperature instantaneously after the application of a field. Since the setup allows the storage of data for each cycle of the applied field, this can be used to study the response of ferroelectric domains in an applied alternating field with time on unpoled or poled samples. The setup is interfaced with a personal computer to obtain directly the values of loop parameters.

An automated loop tracer for the study of the growth of ferroelectric hysteresis

The characteristics of materials like ferrites, garnets, ferroelectrics temperaturecompensated dielectrics and copper-coated PTFE-based composites, extensively used in microwave devices are discussed.

/pdf/characteristics-of-materials-for-microwave-devices-3mf5xjhq2c.pdf

Characteristics of materials for microwave devices

In the field of non-contact methodology for the evaluation of carrier transport study, microwave Hall mobility technique using bimodal cavity is the most sensitive method available so far. Though there is no constraint for the use of different types or shapes of the bimodal cavities used, each cavity would have its own advantages and disadvantages. In this respect, it is very important to analyze the sensitivity of different cavities that could be used in this methodology. In this paper, different bimodal cavities [TE112 (X-band) cylindrical and TE111 (P-band) cylindrical, TE101 (X-band) cubical and a rectangular bimodal cavity (X-band resonating with TE103 and TE105 modes)] are used to evaluate the carrier mobility in various semiconductor samples. These cavities are then analyzed in terms of the sensitivity and the percentage of deviation from the DC mobility values.

Analysis of Bimodal Cavities for Microwave Hall Effect Measurements

Study of structural, dielectric and AC conductivity properties of SrMoO4

Mean Molecular polarizabilities, polarizability anisotropies and order parameters are evaluated in members of three homologous series, using two theoretical models. The variation of polarizabilities and their anisotropies with number of carbon atoms in the alkyl chain is studied. The temperature dependence of order parameter is also presented. The results are compared with the reported values and the merits of the different models are discussed.

V. R. K. Murthy

Papers

An automated loop tracer for the study of the growth of ferroelectric hysteresis

Characteristics of materials for microwave devices

Analysis of Bimodal Cavities for Microwave Hall Effect Measurements

Study of structural, dielectric and AC conductivity properties of SrMoO4

Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals