4,729 research outputs found
Airy-function electron localization in the oxide superlattices
Oxide superlattices and microstructures hold the promise for creating a new
class of devices with unprecedented functionalities. Density-functional studies
of the recently fabricated superlattices of lattice-matched perovskite
titanates (SrTiO3)n/(LaTiO3)m reveal a classic wedge-shaped potential
originating from the Coulomb potential of a charged sheet of La atoms. The
potential in turn confines the electrons in the vicinity of the sheet, leading
to an Airy-function localization of the electron states. Magnetism is
suppressed for structures with a single LaTiO3 monolayer, while the bulk
antiferromagnetism is recovered in the structures with a thicker LaTiO3, with a
narrow transition region separating the magnetic LaTiO3 and the non-magnetic
SrTiO3
Effect of Local Magnetic Moments on the Metallic Behavior in Two Dimensions
The temperature dependence of conductivity in the metallic phase
of a two-dimensional electron system in silicon has been studied for different
concentrations of local magnetic moments. The local moments have been induced
by disorder, and their number was varied using substrate bias. The data suggest
that in the limit of the metallic behavior, as characterized by
, is suppressed by an arbitrarily small amount of scattering by
local magnetic moments.Comment: 4 pages, revtex, plus four encapsulated postscript figure
Absence of Localization in Certain Field Effect Transistors
We review some experimental and theoretical results on the metal-to-insulator
transition (MIT) observed at zero magnetic field (B=0) in several
two-dimensional electron systems (2DES). Scaling of the conductance and
magnetic field dependence of the conductance provide convincing evidence that
the MIT is driven by Coulomb interactions among the carriers and is
dramatically sensitive to spin polarization of the carriers.Comment: 8 pages, LaTeX, figure label change
Metal-insulator transition and glassy behavior in two-dimensional electron systems
Studies of low-frequency resistance noise demonstrate that glassy freezing
occurs in a two-dimensional electron system in silicon in the vicinity of the
metal-insulator transition (MIT). The width of the metallic glass phase, which
separates the 2D metal and the (glassy) insulator, depends strongly on
disorder, becoming extremely small in high-mobility (low-disorder) samples. The
glass transition is manifested by a sudden and dramatic slowing down of the
electron dynamics, and by a very abrupt change to the sort of statistics
characteristic of complicated multistate systems. In particular, the behavior
of the second spectrum, an important fourth-order noise statistic, indicates
the presence of long-range correlations between fluctuators in the glassy
phase, consistent with the hierarchical picture of glassy dynamics.Comment: Contribution to conference on "Noise as a tool for studying
materials" (SPIE), Santa Fe, New Mexico, June 2003; 15 pages, 12 figs.
(includes some low-quality figs; send e-mail to get high-quality figs.
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