Lab: (919) 660-2458, (919) 660-2463
Group offices: (919) 660-2659, (919) 660-2498
CNT (faint diagonal line) with leads
Bird's eye view of the sample
(1 mm x 1 mm)
Nanowires and Graphene
We study electrical properties of carbon nanotubes, nanowires and graphene, which are contacted by metal leads made by e-beam lithography (as shown in the image). The measurements are performed at temperatures down to 15 mK. Below are the links to our select publications, broken by subject:
1) Resonant tunneling with dissipation.
●Quantum Phase Transition in a resonant level with dissipation (Nature 2012):
Quantum phase transition in a resonant level coupled to interacting leads
●Resonant tunneling with dissipation (PRB 2009):
Resonant tunneling in a dissipative environment
2) Orbital degeneracy and the SU(4) Kondo effect in nanotubes.
●SU(4) Kondo experiment 1 (PRL 2007):
Evolution of Transport Regimes in Carbon Nanotube Quantum Dots
●SU(4) Kondo experiment 2 (PRB 2007):
SU(4) and SU(2) Kondo Effects in Carbon Nanotube Quantum Dots
●SU(4) Kondo theory (PRL 2008):
Zero-Bias Conductance in Carbon Nanotube Quantum Dots
●Orbital degeneracy (PRB 2006):
Persistent orbital degeneracy in carbon nanotubes
3) Nanotubes - other : Kondo-box, 4-probe.
●Kondo box in a CNT (PRB 2010):
Two-stage Kondo effect and Kondo-box level spectroscopy in a carbon nanotube
●Non-local 4 probe measurements and mode equilibration (PRB 2007):
Four-Probe Measurements of Carbon Nanotubes with Narrow Metal Contacts
4) Graphene with superconducting contacts.
●Phase diffusion (PRL 2011):
Phase Diffusion in Graphene-Based Josephson Junctions
5) Aluminum nanowires (collaboration with A. Chang).
●Single phase slips in Aluminum nanowires (PRL 2011):
Switching Currents Limited by Single Phase Slips in One-Dimensional Superconducting Aluminum Nanowires,
●Retrapping in Aluminum nanowires (PRB 2011):
Retrapping Current, Self-Heating, and Hysteretic Current-Voltage Curves in Ultra-Narrow Superconducting Aluminum Nanowires
AFM image of a DNA lattice
nanostructures based on self-assembling DNA
In this research project, we aim to develop efficient methods to assemble nanoscale circuits. The structures are based on self-assembled DNA templates (image on the left), which will be partially metallized or will have inorganic nanoscale objects tethered to them (More Info). The work is done in collaboration with Thom LaBean's group.
1) DNA Nanostructures.
●Fabrication of pre-design metallic nanostructures using DNA origami (Nano Letters 2011):
Connecting the nanodots: programmable nanofabrication of fused metal shapes on DNA templates.
● Review article (Soft Matter 2011):
Self-assembling DNA templates for programmed artificial biomineralization
●Development of the cross-shaped DNA tile lattice and DNA nanotubes, their metalization (Science 2003):
DNA-Templated Self-Assembly of Protein Arrays and Highly Conductive Nanowires
●Most recent developments of the cross-shaped DNA tiles system (JACS 2009):
Stepwise Self-Assembly of DNA Tile Lattices Using dsDNA Bridges
2) Electrical measurements of metallized DNA structures.
●Silver wires based on DNA - optimized recipe (APL 2006):
Optimized fabrication and electrical analysis of silver nanowires templated on DNA molecules
●Chemical patterning of e-beam lithographically prepared substrates for making Single-Electron Transistors and other structures (APL 2008):
Chemical patterning of silicon dioxide substrates for selective deposition of gold nanoparticles and fabrication of single-electron transistors
Scanning gate image of a nanotube
in the Coulomb blockade regime
We have built two low-temperature Atomic Force Microscopes (AFM) and use them to study electrical properties of carbon nanotubes. Conductive tip AFM allows us to image nanotubes on a non-conductive substrate and then study them by tunneling spectroscopy and scanning gate microscopy.
●Tunneling spectroscopy and manipulation (APL 2007):
Low-Temperature Conductive Tip Atomic Force Microscope for Carbon Nanotube Probing and Manipulation
●Tip as a scanning gate: effect on the orbital degeneracy (JETP Lett 2009):
Dependence of transport through carbon nanotubes on local Coulomb potential