Using the valence-bond-solid (VBS) approach and the Schwinger boson mean field approximation, we study the dependence of the Haldane gap of a spin-1 linear chain Heisenberg antiferromagnet on impurity doping with different spins. The impurity spins affect the singlet pairing order parameter ∆ and the constraint factor λ. As a result, the Haldane gap is reduced by a factor ∼ n 2/3 i , with ni as...

We discuss the broadening of ground-state to bounded excited-state transitions of shallow donors in strongly compensated n-type Ge : (As,Ga) in the presence of electric fields and their gradients, arising from randomly distributed ionized impurities. Quantitative comparison of the experimentally obtained linewidths with Monte Carlo simulation results makes possible, a unique determination of th...

In our work we study the doping behaviour of sulphur in Czochralski grown GaSb by means of the high resolution Fourier transform infrared spectroscopy and the secondary ion mass spectroscopy. We have revealed that the sulphur impurity forms an effective mass like donor state bound to the L-minimum of the conduction band. From the far infrared spectrum of this donor we derive the effective band ...

Theoretical and numerical analysis is presented for kinetics of impurity segregation at the boundaries of a thin layer of substance dividing two different materials. Time dependences of boundary impurity concentrations and concentration profiles within the film have been obtained. Depending on the energy of impurity interaction with the boundaries and the temperature, some criteria were establi...

Impurity removal is a momentous part of zinc hydrometallurgy process. In this paper, hybrid modeling method mechanism and parameter estimation was proposed on the basis not changing actual production process lead-zinc smeltery. Firstly, overall nonlinear dynamic model established, then deviation between theoretical value detected outlet ion concentration taken as objective function to establish...

background: consistency, backing process and content differences could influence cariogenic potential of foods. the aim was to compare plaque ph changes following consumption of two types of bread with different physical characteristics. methods: in this clinical trial, interproximal plaque ph of 10 volunteers with high risk of dental caries (saliva streptococcus mutans > 10 5 , high dental car...

A theory of nonmagnetic impurities in an anisotropic superconductor including the effect of anisotropic (momentum-dependent) impurity scattering is given. It is shown that for a strongly anisotropic scattering the reduction of the pair-breaking effect of the impurities is large. For a significant overlap between the anisotropy functions of the scattering potential and that of the pair potential...