Showing papers on "Mott transition published in 1987"
TL;DR: In this article, it was shown that the Ba or La f-orbitals play an important role in softening these plasmon modes and strengthening the electron-plasmon coupling.
35 citations
TL;DR: Low-T transport data on n-type GaAs in several regimes from insulating to metallic is presented and evidence is presented for weak localization and then normal metallic behavior for higher impurity concentrations.
Abstract: Low-T transport data on n-type GaAs in several regimes from insulating to metallic is presented. On the insulating side of the Mott transition, it is shown that the power s in the variable-range-hopping law, ${\ensuremath{\sigma}}_{v}$=${\ensuremath{\sigma}}_{0}$exp[-(${T}_{0}$/T${)}^{s}$], which is found to be (1/4 for pure enough samples, can reach (1/2 for a narrow range of higher impurity concentrations. A small metal-like contribution to the conductivity can explain the observed shift in s and is supported by Hall-mobility data. Consequently, the corresponding behavior can hardly be interpreted as due to a Coulomb gap in the density of impurity states. Evidence is presented for weak localization and then normal metallic behavior for higher impurity concentrations.
25 citations
TL;DR: In this article, the Hall coefficients and resistivity of MBE-grown Si, doped with P, As, Sb, B, and Ga in the concentration range 1014 to 1020 cm−3, were carried out at 77 K and at 300 K.
Abstract: Measurements of the Hall coefficients and of the resistivity of MBE-grown Si, doped with P, As, Sb, B, and Ga in the concentration range 1014 to 1020 cm−3, were carried out at 77 K and at 300 K. With the exception of Ga-doped Si, the measured mobilities were close to or higher than those of bulk materials at both temperatures. The Mott metal/non-metal transition has been observed in the present epitaxial materials and the measured values for the critical impurity concentration at which the transition occurs, agree with values reported by other workers for bulk silicon.
18 citations
TL;DR: The x-dependence of the a-and c-axis relative resistances and the near-normal reflectance of the metal-ammonia ternary graphite intercalation compound K(NH 3 ) x C 24 has been studied in the range 0 ≦ x ≦ 4.38 as mentioned in this paper.
9 citations
TL;DR: In this article, the photoluminescence spectra of GaSe at a bath temperature of 2K were measured at electron-hole densities ranging from below to above the screening limit for the free direct excitons.
8 citations
01 Jan 1987
TL;DR: In this article, the authors consider systems with electron densities reduced substantially below those of ordinary metals, such as expanded elemental liquid metals, solutions of metals in non-metals, or strongly interacting liquid alloys such as Cs-Au.
Abstract: It is a familiar fact that electrons in most elemental liquid metals and many liquid alloys behave as if they are nearly free. This is a consequence of the high conduction electron densities in these systems and resultant screening of the electron-ion interaction. The effects of electron-electron interactions are also relatively small in ordinary metals except for corrections to a few physical properties such as the magnetic susceptibility. The situation is quite different, however, if we consider systems with electron densities reduced substantially below those of ordinary metals. These conditions may be found in a number of liquids such as expanded elemental liquid metals, solutions of metals in non-metals, or strongly interacting liquid alloys such as Cs-Au. Structural disorder becomes much more important as the full unscreened ionic potentials are exposed and may lead to electron localization by the Anderson transition or other means such as self-trapping. Alternatively, electron-electron interactions drive the Mott transition and cause localization at low densities in systems with one electron per atom. In some systems, of course, both effects may be at work.