4 research outputs found
An epigraphene platform for coherent 1D nanoelectronics
Exceptional edge state ballistic transport, first observed in graphene nanoribbons grown on the sidewalls of trenches etched in electronics grade silicon carbide even at room temperature, is shown here to manifest in micron scale epigraphene structures that are conventionally patterned on single crystal silicon carbide substrates. Electronic transport is dominated by a single electronic mode, in which electrons travel large distances without scattering, much like photons in an optical fiber. In addition, robust quantum coherence, non-local transport, and a ground state with half a conductance quantum are also observed. These properties are explained in terms of a ballistic edge state that is pinned at zero energy. The epigraphene platform allows interconnected nanostructures to be patterned, using standard microelectronics methods, to produce phase coherent 1D ballistic networks. This discovery is unique, providing the first feasible route to large scale quantum coherent graphene nanoelectronics, and a possible inroad towards quantum computing
Protected transport in the epigraphene edge state
The graphene edge state has long been predicted to be a zero energy,
one-dimensional electronic waveguide mode that dominates transport in neutral
graphene nanostructures, with potential application to graphene devices.
However, its exceptional properties have been observed in only a few cases,
each employing novel fabrication methods without a clear path to large-scale
integration. We show here that interconnected edge-state networks can be
produced using non-conventional facets of electronics grade silicon carbide
wafers and scalable lithography, which cuts the epitaxial graphene and
apparently fuses its edge atoms to the silicon carbide substrate. Measured
epigraphene edge state (EGES) conduction is ballistic with mean free paths
exceeding tens of microns, thousands of times greater than for the diffusive 2D
bulk. It is essentially independent of temperature, decoupled from the bulk and
substantially immune to disorder. Remarkably, EGES transport involves a
non-degenerate conductance channel that is pinned at zero energy, yet it does
not generate a Hall voltage, implying balanced electron and hole components.
These properties, observed at all tested temperatures, magnetic fields, and
charge densities, are not predicted by present theories, and point to a
zero-energy spin one-half quasiparticle, composed of half an electron and a
half a hole moving in opposite directions
Effects of Non-native Interactions on Frustrated Proteins Folding under Confinement
In
vitro, kinetically significant non-native interactions have
been identified experimentally during the folding of proteins Im7,
Im9, and A39V/N53P/V55L Fyn SH3 domain. To understand the role of
non-native interactions on the folding of some frustrated proteins
in chaperone, we employed native-centric models with and without additional
transferable, sequence-dependent non-native hydrophobic interactions
to comparatively study the folding behaviors of the three proteins
confined in spherical cages. Under purely repulsive confinement, as
a decrease of cavity size, the non-native interactions increase, especially
in the unfolded state, enhancing the roughness of the folding energy
landscape. As a result, the increase in native stability for the three
proteins by the model incorporated non-native interactions (db + MJ<i>h</i>Ï• model) is much smaller than that by the purely
native-centric model (desolvation-barrier (db) model); the acceleration
of folding simulated by the db + MJ<i>h</i>Ï• model
is much slower than that via the db model; in particular, the folding
rate of Im7 decreases when reducing the cavity size under zero-denaturant
condition. The repulsive confinement can also promote formation of
specific non-native contacts in the transition state and favor more
folding pathways passing through the misfolded state, leading to a
higher population of the misfolded intermediate. In an attractive
cage, the attractive interactions could inhibit the formation of intrachain
non-native contacts and provide alternate folding pathways to the
native state so that the population of the misfolded intermediate
decreases when increasing the strength of attractive interaction between
the substrate protein and cavity wall. This study should be helpful
in general to understand how the chaperonins reshape the folding energy
landscape of some frustrated proteins
An epigraphene platform for coherent 1D nanoelectronics
Exceptional edge state ballistic transport, first observed in graphene nanoribbons grown on the sidewalls of trenches etched in electronics grade silicon carbide even at room temperature, is shown here to manifest in micron scale epigraphene structures that are conventionally patterned on single crystal silicon carbide substrates. Electronic transport is dominated by a single electronic mode, in which electrons travel large distances without scattering, much like photons in an optical fiber. In addition, robust quantum coherence, non-local transport, and a ground state with half a conductance quantum are also observed. These properties are explained in terms of a ballistic edge state that is pinned at zero energy. The epigraphene platform allows interconnected nanostructures to be patterned, using standard microelectronics methods, to produce phase coherent 1D ballistic networks. This discovery is unique, providing the first feasible route to large scale quantum coherent graphene nanoelectronics, and a possible inroad towards quantum computing