5 research outputs found
Enhanced Magnetoresistance in Molecular Junctions by Geometrical Optimization of Spin-Selective Orbital Hybridization
Molecular junctions based on ferromagnetic
electrodes allow the study of electronic spin transport near the limit
of spintronics miniaturization. However, these junctions reveal moderate
magnetoresistance that is sensitive to the orbital structure at their
ferromagnet–molecule interfaces. The key structural parameters
that should be controlled in order to gain high magnetoresistance
have not been established, despite their importance for efficient
manipulation of spin transport at the nanoscale. Here, we show that
single-molecule junctions based on nickel electrodes and benzene molecules
can yield a significant anisotropic magnetoresistance of up to ∼200%
near the conductance quantum <i>G</i><sub>0</sub>. The measured
magnetoresistance is mechanically tuned by changing the distance between
the electrodes, revealing a nonmonotonic response to junction elongation.
These findings are ascribed with the aid of first-principles calculations
to variations in the metal–molecule orientation that can be
adjusted to obtain highly spin-selective orbital hybridization. Our
results demonstrate the important role of geometrical considerations
in determining the spin transport properties of metal–molecule
interfaces
Field-Effect Transistors Based on WS<sub>2</sub> Nanotubes with High Current-Carrying Capacity
We
report the first transistor based on inorganic nanotubes exhibiting
mobility values of up to 50 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> for an individual WS<sub>2</sub> nanotube. The current-carrying
capacity of these nanotubes was surprisingly high with respect to
other low-dimensional materials, with current density at least 2.4
× 10<sup>8</sup> A cm<sup>–2</sup>. These results demonstrate
that inorganic nanotubes are promising building blocks for high-performance
electronic applications
Defect-Free Carbon Nanotube Coils
Carbon
nanotubes are promising building blocks for various nanoelectronic
components. A highly desirable geometry for such applications is a
coil. However, coiled nanotube structures reported so far were inherently
defective or had no free ends accessible for contacting. Here we demonstrate
the spontaneous self-coiling of single-wall carbon nanotubes into
defect-free coils of up to more than 70 turns with identical diameter
and chirality, and free ends. We characterize the structure, formation
mechanism, and electrical properties of these coils by different microscopies,
molecular dynamics simulations, Raman spectroscopy, and electrical
and magnetic measurements. The coils are highly conductive, as expected
for defect-free carbon nanotubes, but adjacent nanotube segments in
the coil are more highly coupled than in regular bundles of single-wall
carbon nanotubes, owing to their perfect crystal momentum matching,
which enables tunneling between the turns. Although this behavior
does not yet enable the performance of these nanotube coils as inductive
devices, it does point a clear path for their realization. Hence,
this study represents a major step toward the production of many different
nanotube coil devices, including inductors, electromagnets, transformers,
and dynamos
Defect-Free Carbon Nanotube Coils
Carbon
nanotubes are promising building blocks for various nanoelectronic
components. A highly desirable geometry for such applications is a
coil. However, coiled nanotube structures reported so far were inherently
defective or had no free ends accessible for contacting. Here we demonstrate
the spontaneous self-coiling of single-wall carbon nanotubes into
defect-free coils of up to more than 70 turns with identical diameter
and chirality, and free ends. We characterize the structure, formation
mechanism, and electrical properties of these coils by different microscopies,
molecular dynamics simulations, Raman spectroscopy, and electrical
and magnetic measurements. The coils are highly conductive, as expected
for defect-free carbon nanotubes, but adjacent nanotube segments in
the coil are more highly coupled than in regular bundles of single-wall
carbon nanotubes, owing to their perfect crystal momentum matching,
which enables tunneling between the turns. Although this behavior
does not yet enable the performance of these nanotube coils as inductive
devices, it does point a clear path for their realization. Hence,
this study represents a major step toward the production of many different
nanotube coil devices, including inductors, electromagnets, transformers,
and dynamos
Defect-Free Carbon Nanotube Coils
Carbon
nanotubes are promising building blocks for various nanoelectronic
components. A highly desirable geometry for such applications is a
coil. However, coiled nanotube structures reported so far were inherently
defective or had no free ends accessible for contacting. Here we demonstrate
the spontaneous self-coiling of single-wall carbon nanotubes into
defect-free coils of up to more than 70 turns with identical diameter
and chirality, and free ends. We characterize the structure, formation
mechanism, and electrical properties of these coils by different microscopies,
molecular dynamics simulations, Raman spectroscopy, and electrical
and magnetic measurements. The coils are highly conductive, as expected
for defect-free carbon nanotubes, but adjacent nanotube segments in
the coil are more highly coupled than in regular bundles of single-wall
carbon nanotubes, owing to their perfect crystal momentum matching,
which enables tunneling between the turns. Although this behavior
does not yet enable the performance of these nanotube coils as inductive
devices, it does point a clear path for their realization. Hence,
this study represents a major step toward the production of many different
nanotube coil devices, including inductors, electromagnets, transformers,
and dynamos