Radiation-induced magnetoresistance oscillations in two-dimensional electron systems under bichromatic irradiation

We analyze the magnetoresistance $R_{xx}$ oscillations in high-mobility two-dimensional electron systems induced by the combined driving of two radiation fields of frequency $\omega_1$ and $\omega_2$, based on the balance-equation approach to magnetotransport for high-carrier-density systems in Faraday geometry. It is shown that under bichromatic irradiation of $\omega_2\sim 1.5 \omega_1$, most of the characterstic peak-valley pairs in the curve of $R_{xx}$ versus magnetic field in the case of monochromatic irradiation of either $\omega_1$ or $\omega_2$ disappear, except the one around $\omega_1/\omega_c\sim 2$ or $\omega_2/\omega_c\sim 3$. $R_{xx}$ oscillations show up mainly as new peak-valley structures around other positions related to multiple photon processes of mixing frequencies $\omega_1+\omega_2$, $\omega_2-\omega_1$, etc. Many minima of these resistance peak-valley pairs can descend down to negative with enhancing radiation strength, indicating the possible bichromaticzero-resistance states.Comment: 5 pages, 3 figures. Accepted for publication in Phys. Rev.

SU(N) Coherent States

We generalize Schwinger boson representation of SU(2) algebra to SU(N) and define coherent states of SU(N) using $2(2^{N-1}-1)$ bosonic harmonic oscillator creation and annihilation operators. We give an explicit construction of all (N-1) Casimirs of SU(N) in terms of these creation and annihilation operators. The SU(N) coherent states belonging to any irreducible representations of SU(N) are labelled by the eigenvalues of the Casimir operators and are characterized by (N-1) complex orthonormal vectors describing the SU(N) manifold. The coherent states provide a resolution of identity, satisfy the continuity property, and possess a variety of group theoretic properties.Comment: 25 pages, LaTex, no figure

Spin ordering and electronic texture in the bilayer iridate Sr3_3Ir2_2O7_7

Through a neutron scattering, charge transport, and magnetization study, the correlated ground state in the bilayer iridium oxide Sr$_3$Ir$_2$O$_7$ is explored. Our combined results resolve scattering consistent with a high temperature magnetic phase that persists above 600 K, reorients at the previously defined $T_{AF}=280$ K, and coexists with an electronic ground state whose phase behavior suggests the formation of a fluctuating charge or orbital phase that freezes below $T^{*}\approx70$ K. Our study provides a window into the emergence of multiple electronic order parameters near the boundary of the metal to insulator phase transition of the 5d $J_{eff}=1/2$ Mott phase.Comment: Revised text and figures. 4 pages, 4 figure

Analysis of Flow Fields in a Flexible Tube with Periodic Constriction

Numerical techniques based on pressure-velocity formulation have been adopted to solve approximately, the governing equations for viscous flows through a tube (simulating an artery) with a periodic constriction. The effect of the constriction as well as the rigid of the tube, on the flow characteristics, and its consequences for arterial disease is the focus of this investigation. The unsteady incompressible Navier-Stokes equations are solved by using the finite-difference technique in staggered grid distribution. The haemodynamic factors like wall shear stress, pressure and velocity are analyzed through their graphical representations. Maximum resistance is attained in case of rigid stenosed tube rather than the flexible one. The main result is to contribute that the recirculating region is larger in case of a rigid tube than that of flexible one

Marine fisheries in Gujarat

A brief account of marine fish landings in Gujarat during 1985- 95 is given in this paper. Contribution of different gears along with the CPUE and the regionwise as well as groupwise details are also presented. The status and prospect of marine fisheries ofihe state is discussed with the aid of last 5 decades landing data