Dependence Of Magnetoconductivity Research Articles

Effect of Electron Correlation on Angular Dependence of Magnetoconductivity

An effect of electron correlation is studied in an angular dependence of magnetoconductivity of quasi one-dimensional organic conductors. We investigate the effect of both quasi-particle’s lifetime and velocity due to the electron correlation near SDW in the magnetoconductivity. We found that the momentum dependence of lifetime strongly suppresses the one-dimensional axis magnetoconductivity at a magic angle θ=45°. On the other hand, the change of the momentum dependence of the velocity originating from the electron correlation enhances the interchain magnetoconductivity at θ=0°. These effects are explained from the momentum dependence of lifetime and velocity over the electron’s commensurate orbital on Fermi surface at the magic angles.

Effect of electron correlation near-field-induced SDW on angle dependent magnetoresistance oscillation

An effect of electron correlation on an angular dependence of magnetoconductivity is investigated in quasi-one-dimensional organic conductors. The effect is studied on the basis of momentum dependence of both quasi-particle's lifetime and velocity near SDW. We find that the momentum dependence of quasi-particle's lifetime mainly governs the angular dependence of one-dimensional axis magnetoconductivity. On the other hand, the change of the momentum dependence of velocity originating from electron correlation gives the dominant effects to angular dependence of the interchain axis magnetoconductivity. These effects of electron correlation are explained from the connection of the momentum dependence of lifetime and velocity with the momentum dependence of commensurate orbital on Fermi surface in magnetic fields.

Effects of Electron Correlation near Spin-Density-Wave on Angle Dependence of Magnetoconductivity

The effect of electron correlation on the angle dependence of magnetoconductivity is studied in quasi-one-dimensional organic conductors. We investigated the effect on the basis of the momentum dependence of both quasi-particle's lifetime and velocity near the spin-density-wave (SDW). We found that the momentum dependence of quasi-particle's lifetime mainly governs the angle dependence of one-dimensional axis magnetoconductivity. On the other hand, the change in velocity originating from the electron correlation gives the dominant effects on the angle dependence of the interchain axis magnetoconductivity. The effect of electron correlation is clarified from the association of the momentum dependences of lifetime and velocity with the momentum dependences of commensurate orbitals on a Fermi surface in magnetic fields.

Effect of electron correlation on angular dependence of magnetoconductivity

Effect of electron correlation on angular dependence of magnetoconductivity

HIGH FIELD MAGNETOCONDUCTIVITY OF IODINE DOPED HELICAL POLYACETYLENE

The effect of interfibrillar interaction on the charge transport of doped polyacetylene is investigated by studying the high field magnetoconductivity of iodine doped helical polyacetylene. The zero-field resistivity ratio, ρ r = ρ(1.2 K )/ρ(300 K ), is comparable to that of stretch-oriented high-density polyacetylene, which indicates the partial alignment of chains inside a polymer fiber. At low magnetic fields, the small negative component of magnetoconductivity was observed and its magnitude increases as the ρ r value increases. In the high field region, the magnetoconductivity is positive and it clearly shows the linear dependence on the magnetic field up to H = 30 T. The linear field dependence of magnetoconductivity is different from what is expected in the three-dimensional weak localization picture. For the same ρ r value samples, the magnitude of negative magnetoconductivity of S-polyacetylene is much bigger than that of R-polyacetylene, which could be attributed to the difference in the degree of helicity determining the strength of interfibrillar interaction.

Analysis of negative magnetoresistance: Statistics of closed paths. I. Theory

Statistics of closed paths in two-dimensional (2D) systems, which just determines the interference quantum correction to conductivity and anomalous magnetoconductance, has been studied by computer simulation of a particle motion over the plane with randomly distributed scatterers. Both ballistic and diffusion regimes have been considered. The results of simulation have been analyzed in the framework of diffusion approximation. They are used for calculation of the magnetic-field dependence of magnetoconductance in the model 2D system. It is shown that the anomalous magnetoconductance can be, in principle, described by the well-known expression, obtained in the diffusion approximation, but with the prefactor less than unity and phase breaking, which differs from true value.

Anisotropic magnetoconductance in metallic doped Ge:Sb

The dependence of magnetoconductance on the direction of a magnetic field is measured in four valley and stressed single valley lightly metallic Ge:Sb, and is analyzed on the basis of the localization and the interaction theories of dirty metal. Positive magnetoconductance is described fairly well by the localization theory in its anisotropy. The theory is consistent with the experiment also in its magnitude in single valley case but is too large in four valley case. Negative magnetoconductance is analyzed as a sum of the components of orbital and g-factor anisotropy. The latter contribution is found to be dominant, though its magnitude is larger than the interaction theory both in four and single valley cases.

The Cut-Off Dependence of Magnetoconductivity Due to Localization in 3-Dimensional Systems

The results of numerical calculation for magnetoconductivity due to localization in 3-dimensional systems in weakly localized regime are given by taking into account the finiteness of cut-off parameters; z -component of momentum and the quantum number for orbital splitting. We find that the finiteness of cut-off parameters makes decrease the magnetoconductivity compared to Kawabata's results which are obtained on the assumption of cut-off parameters being infinite. The amount of decrease in magnetoconductivity increases as the magnetic field is increased. A saturation of magnetoconductivity due to localization will be observed as a function of field.

Galvanomagnetic Effect in TlCl

Hall effect and magnetoconductivity of photocarriers in TlCl have been measured by a transient method between 90°K and 1.8°K. It is found that the Hall effect changes its sign at some critical temperature, indicating that the conduction is of two-carrier. Above the critical temperature, the dominant contribution to the current is by electrons and below it by positive holes. Between 1.8°K and 10°K, high Hall mobilities of positive holes of more than 5×10 4 cm 2 /volt sec are observed. From the angular dependence of magnetoconductivity at this low temperature, the shape of the constant energy surface at the top of the valence band is deduced.