Showing papers on "Einstein relation published in 1990"
TL;DR: In this article, random walks are used to obtain the diffusion constant for continuum percolation models of composite materials in two and three dimensions, and an Einstein relation is then used to find the conductivity.
Abstract: Random walks are used to obtain the diffusion constant for continuum percolation models of composite materials in two and three dimensions. An Einstein relation is then used to find the conductivity. The same calculation gives the dielectric constant for the composite. First-passage-time methods and special boundary conditions are used for systems where both materials have finite conductivity, where one component is a superconductor, and where one component does not conduct. The percolation models consist of randomly placed overlapping spheres in three dimensions or disks in two dimensions. Our results are consistent with known results where applicable and are far better than effective medium theories. Estimates for anomalous diffusion exponents at percolation were also found.
29 citations
TL;DR: In this article, the effects of varying the orientation of a quantizing magnetic field on the Einstein relation for the diffusivity-mobility ratio of the electrons in stressed Kane-type semiconductors, taking stressed n-InSb as an example, were investigated theoretically.
Abstract: An attempt is made to investigate theoretically the effects of varying the orientation of a quantizing magnetic field on the Einstein relation for the diffusivity-mobility ratio of the electrons in stressed Kane-type semiconductors, taking stressed n-InSb as an example. It is found, that the above ratio oscillates in a periodic manner with changes in the orientation of the magnetic field and increases with increasing electron concentration as expected in degenerate semiconductors. The ratio also exhibits oscillatory magnetic field dependence since the origin of the oscillations in the Einstein relation is the same as that of the Shubnikov de Hass oscillations. The corresponding well-known results for unstressed parabolic energy bands are also obtained from the generalized expressions as special cases.
21 citations
TL;DR: In this paper, the authors analyzed the experimental data concerning fusion cross sections, spin distributions and their moments in the framework of a transport model by solving Langevin equations based on the surface friction model and showed that experiment and theory are in good agreement at energies above the funsion barrier.
16 citations
TL;DR: In this paper, a multidimensional Fokker-Planck-Kramers equation for rotational relaxation of small solutes in complex liquids is developed wherein collective solvent effects are explicitly represented by rotating torques and stochastic fields.
13 citations
TL;DR: In this article, a computer simulation is used to investigate the motion of a marked particle of mass M in a free gas of particles with massm = 1, for large times.
Abstract: A computer simulation is used to investigate the motion of a marked particle of massM in a free gas of particles with massm=1, for large times. Previous results seem to indicate a non-Wiener behavior for the rescaled trajectory whenM≠m. The results reported here, with better statistics, are compatible with the Wiener hypothesis. The Einstein relation between mobility and diffusion coefficient is also investigated. The results indicate that it holds both forM=m and forM≠m.
3 citations
TL;DR: In this paper, a newly derived electron energy spectrum in QW of tetragonal semiconductors, within the framework of (IEq1} method by considering all types of anisotropies of the energy band parameters, was derived.
Abstract: We have studied the Einstein relation for the diffusivity. mobility ratio (DMR) on the basis of a newly derived electron energy spectrum in QW of tetragonal semiconductors, within the framework of (IEq1} method by considering all types of anisotropies of the energy band parameters. It is found, taking n-Cd3As2 as an example that the DUTZ increases with electron concentration and decreases with film thickness in an oscillatory manner respectively. The theoretical results are in good aoreement with the suggested experimental method of determining the MIR in degenerate semiconductors having arbitrary dispersion law.
3 citations
01 Oct 1990
TL;DR: In this paper, an attempt was made to study the Einstein relation for the diffuaivlty-mobility ratio of the electron in quantum well wires of Small-gap Semiconductors in the preaence of crossed electric and magnetic fields on the basis of a newly derived electron energy spectrum considering all types anisotropies in the band parameters.
Abstract: An attempt is made to study the Einstein relation for the diffuaivlty-mobility ratio of the electron in quantum well wires of Small-gap Semiconductors in the preaence of crossed electric and magnetic fields on the basis of a newly derived electron energy spectrum considering all types anisotropies in the band parameters. It is found taking n-CdGeAs as an example that, the same ratio increases with electron concentration and electric field in an oscillatory way. Besides, it decreases with thickness and the crystal field parameter Influence sinifigantly the ratio in the whole range of variables considered. We have also suggested an experimental method of determining the Einstein relation in degenerate materials having arbitrary dispersion law. The expression for quanturn well wires of parabolic semi-conductors are also obtained from our generalised expressions derived in the absence of cross field configuration.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
3 citations