High Tc Superconductors -- A Variational Theory of the Superconducting State

We use a variational approach to gain insight into the strongly correlated d-wave superconducting state of the high Tc cuprates at T=0. We show that strong correlations lead to qualitatively different trends in pairing and phase coherence: the pairing scale decreases monotonically with hole doping while the SC order parameter shows a non-monotonic dome. We obtain detailed results for the doping-dependence of a large number of experimentally observable quantities, including the chemical potential, coherence length, momentum distribution, nodal quasiparticle weight and dispersion, incoherent features in photoemission spectra, optical spectral weight and superfluid density. Most of our results are in remarkable quantitative agreement with existing data and some of our predictions, first reported in Phys. Rev. Lett. {\bf 87}, 217002 (2001), have been recently verified.Comment: (Minor revisions, 1 figure added, version to appear in PRB) 23 RevTeX pages, 11 eps figs, long version of cond-mat/0101121, contains detailed comparisons with experiments, analytical insights, technical aspects of the calculation, and comparison with slave boson MF

Surface ordering of MBE grown 001 gallium(05) aluminum(05) arsenic: A theoretical study

The surface kinetics of MBE growth of 001 {dollar}Ga\sb{x}Al\sb{1-x}As{dollar} is studied theoretically using the stochastic model which is based on the master equation approach and random distribution approximation. The kinetic processes included in the model are adsorption and surface migration. The surface ordering kinetics is studied as function of fluxes, flux ratio and substrate temperature. The growth parameters employed for the monatomic spices As are: fluxes 2{dollar}\sp\circ{dollar} A/sec, for cations with the cation to anion flux ratios 1: 10, and 1: 20. The growth parameter employ for the diatomic spices {dollar}As\sb2{dollar} are: fluxes 2{dollar}\sp\circ{dollar} A/sec. for cations with the cation to anion flux ratios 1: 10, 1: 20, and 1: 30, for cations to anions. The degree of ordering was obtained in terms of short range order (SRO), parameter. The surface ordering kinetics observed can be described in terms of effective surface migration rates of cations as follows. Lower temperature higher flux ratio results in smaller effective surface migration rates for cation. Beyond transition temperature the thermal energy, {dollar}\kappa\sb{B}T{dollar}, is large enough to break the Al-Ga bonds and causes thermal randomization of the Ga-Ga, Al-Al, and Ga-Al bonds. (Abstract shortened by UMI.)

Particle-hole character of the Higgs and Goldstone modes in strongly-interacting lattice bosons

We study the low-energy excitations of the Bose-Hubbard model in the strongly-interacting superfluid phase using a Gutzwiller approach and extract the single-particle and single-hole excitation amplitudes for each mode. We report emergent mode-dependent particle-hole symmetry on specific arc-shaped lines in the phase diagram connecting the well-known Lorentz-invariant limits of the Bose-Hubbard model. By tracking the in-phase particle-hole symmetric oscillations of the order parameter, we provide an answer to the long-standing question about the fate of the pure amplitude Higgs mode away from the integer-density critical point. Furthermore, we point out that out-of-phase oscillations are responsible for a full suppression of the condensate density oscillations of the gapless Goldstone mode. Possible detection protocols are also discussed.Comment: 6 pages, 3 figure

A Study on Household Management, Dietary Practicies and Child Rearing Practicies of Working and Non-working Women of Rajkot City

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Studies on some important Heterocyclic Moieties

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