• Volume 78, Issue 1

January 2012,   pages  1-164

• Grazing incidence polarized neutron scattering in reﬂection geometry from nanolayered spintronic systems

This review summarizes recent experimental investigations using neutron scattering on layered nanomagnetic systems (accentuating my contribution), which have applications in spintronics also. Polarized neutron investigations of such artiﬁcially structured materials are basically done to understand the interplay between structure and magnetism conﬁned within the nanometer scale that can be additionally depth-resolved. Details of the identiﬁcation of buried domains and their nature of lateral and vertical correlations within the systems are important. A particularly interesting aspect that has emerged over the years is the capability to measure polarized neutron scattering in directions parallel and perpendicular to the applied ﬁeld direction (which is also the quantization axis for neutron polarizations). This was added with the capability of measuring in specular as well as in off-specular geometry. Distorted wave Born approximation (DWBA) theory for neutrons has proved to be a remarkable development in the quantitative analysis of the scattering data measured simultaneously for specular and off-specular modes within the same framework. In particular, the depth and lateral distribution of the ferromagnetic spins relative to the interface within interlayercoupled or exchange-coupled system has been extensive. For example, twisted magnetization state at interlayer coupled interfaces or intricacies of symmetric and asymmetric magnetization reversals along with suppression of training effect in exchange coupled system was microscopically identiﬁed using neutron scattering only. The investigation on the distribution of magnetic species within dilute ferromagnetic semiconductor superlattices, with low angle neutron scattering, has played a crucial role both from practical and fundamental research points of view.

• Analytical and numerical solutions of the Schrödinger–KdV equation

The Schrödinger–KdV equation with power-law nonlinearity is studied in this paper. The solitary wave ansatz method is used to carry out the integration of the equation and obtain one-soliton solution. The $G'/G$ method is also used to integrate this equation. Subsequently, the variational iteration method and homotopy perturbation method are also applied to solve this equation. The numerical simulations are also given.

• Approximate solutions of theWei Hua oscillator using the Pekeris approximation and Nikiforov–Uvarov method

The approximate analytical bound-state solutions of the Schrödinger equation for the Wei Hua oscillator are carried out in N-dimensional space by taking Pekeris approximation scheme to the orbital centrifugal term. Solutions of the corresponding hyper-radial equation are obtained using the conventional Nikiforov–Uvarov (NU) method.

• A higher-dimensional Bianchi type-I inﬂationary Universe in general relativity

A ﬁve-dimensional Bianchi type-I inﬂationary Universe is investigated in the presence of massless scalar ﬁeld with a ﬂat potential. To get an inﬂationary Universe, a ﬂat region in which the potential $V$ is constant is considered. Some physical and kinematical properties of the Universe are also discussed.

• Optical probing of Eu ions conﬁned in an RF trap

The Eu ions conﬁned in an RF quadrupole trap, has been optically detected. Using a tunable dye laser which is pumped by a Nd-YAG pulsed laser system, the resonance ${}^9S_4–6 p_{3/2}$, $J = 5$ transition of the Eu ions have been excited and the resulting ﬂuorescence to the metastable ${}^9 D_{4−6}$ state has been detected. In preparation to determine the ground-state hyperﬁne splitting of the odd isotopes we found the optimum trapping operating point. We have also observed a number of instabilities inside the region of the stability for an ideal trap. These non-linear resonances arise from higher-order contributions to the ideal quadrupole potential.

• Effect of nonthermal ion distribution and dust temperature on nonlinear dust-acoustic solitary waves

Dust-acoustic solitary waves in unmagnetized dusty plasma whose constituents are inertial charged dust grains, Boltzmannian electrons and nonthermal ions have been investigated by taking into account ﬁnite dust temperature. The pseudopotential has been used to study solitary solution. The existence of solitary waves having negative potential is reported.

• Dust-acoustic solitary waves in a dusty plasma with two-temperature nonthermal ions

By using reductive perturbation method, the nonlinear propagation of dust-acoustic waves in a dusty plasma (containing a negatively charged dust ﬂuid, Boltzmann distributed electrons and two-temperature nonthermal ions) is investigated. The effects of two-temperature nonthermal ions on the basic properties of small but ﬁnite amplitude nonlinear dust-acoustic waves are examined. It is found that two-temperature nonthermal ions affect the basic properties of the dust-acoustic solitary waves. It is also observed that only compressive solitary waves exist in this system.

• The width of Liesegang bands: A study using moving boundary model and simulation

The pattern formation in reaction–diffusion systems was studied by invoking the provisions contained in the moving boundary model. The model claims that the phase separation mechanism is responsible for separating the colloidal phase of precipitants into band and non-band regions. The relation between the band separation and its width are invariably related to the concentration of the reacting components. It was observed that this model provides critical condition for the band formation in semi-idealized diffusion systems. An algorithm for generating the band structure was designed, and the simulated pattern shows a close resemblance with the experimentally observed ones.

• Theoretical calculation of the Hall mobility of InN$_x$As$_{1−x}$ alloys when $x = 0.0–0.1$

The Hall mobility of InN$_x$As$_{1−x}$ semiconductor alloys is calculated by solving the Boltzmann transport equation using the iterative method. All the major scattering mechanisms are included in the calculations. The Hall mobilities of InAs and InN0.01As0.99 are presented in the temperature range of 30–600 K. It is shown that incorporation of even small amount of nitrogen leads to an abrupt reduction of the Hall mobility in InN$_x$As$_{1−x}$ at low temperatures. The effect of alloy random scattering on the Hall mobility of InN$_x$As$_{1−x}$ is examined at 77 and 300 K as the mole fraction x varies from 0.0 to 0.1. It is seen that the Hall mobility drops sharply up to $x = 0.02$ for 77 K and reduces slowly as the temperature increases to 300 K compared to 77 K. The Hall mobilities calculated theoretically are compared with the experimental data available in the literature.

• Noncommutative geometry-inspired rotating black hole in three dimensions

We ﬁnd a new rotating black hole in three-dimensional anti-de Sitter space using an anisotropic perfect ﬂuid inspired by the noncommutative black hole. We deduce the thermodynamical quantities of this black hole and compare them with those of a rotating BTZ solution and give corrections to the area law to get the exact nature of the Bekenstein–Hawking entropy.

• # Pramana – Journal of Physics

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