We present measurements of the Fermi surface and underlying band structure of a single layer of indium on Si(111) with square root 7 x square root 3 periodicity. Electrons from both indium valence electrons and silicon dangling bonds contribute to a nearly free, two-dimensional metal on a pseudo-4-fold lattice, which is almost completely decoupled at the… (More)
The spin density wave phase transition in chromium has been studied by angle-resolved photoemission on a (110) surface. The electronic band structure is shown to exhibit backfolding in the antiferromagnetic state. Direct spectroscopic evidence is obtained on the gradual opening of an energy gap at the Fermi level. The gap extends almost isotropically around… (More)
We study the positive solutions to steady state reaction diffusion equations with Dirichlet boundary conditions of the forms: u(0) = 0 = u(1), and −u ′′ = λ[au − bu 2 − c], x ∈ (0, 1 2), λ[au − bu 2 ], x ∈ (1 2 , 1), (B) u(0) = 0 = u(1). 1 2. Such steady state equations arise in population dynamics with logistic type growth and constant yield harvesting.… (More)
The electronic band structure of the Peierls compound NbSe3 has been explored for its symmetries with microspot synchrotron photoemission. The Fermi level crossings and deviations from one-dimensional behavior are identified. Density-functional calculations of the Fermi surfaces confirm the nesting conditions relevant for the two phase transitions. The… (More)
Self-assembled indium linear chains on the Si(111) surface are found to exhibit instability of the metallic phase and 1D charge density wave (CDW). The room-temperature metallic phase of these chains undergoes a temperature-induced, reversible transition into a semiconducting phase. The 1D CDW along the chains is observed directly in real space by scanning… (More)
We consider reaction diffusion models in population dynamics where the per capita growth rate is a logistic type or a weak Allee type. In particular, we study the effects of nonlinear diffusion (arising due to aggregative population movements) on the steady states. We obtain our results via the quadrature method.
Low-temperature electronic properties of the charge-density-wave system NbSe3 are reported from angle-resolved photoemission at 15 K. The effect of two instabilities q(1) and q(2) on the k-resolved spectral function is observed for the first time. With a pseudogap background, the gap spectra exhibit maxima at Delta*(1) approximately 110 meV and Delta*(2)… (More)