Transport in nanoscale systems

In part I of the Thesis charge ordering and transport in arrays of coated semiconductor nanocrystals (quantum dot arrays) are studied. Charge ordering in dot arrays is considered by mapping the electrons on the dots onto the frustrated spin model on the triangular lattice. A number of phases is identified for this system. Phase diagram is studied by means of the height field order parameter. Novel correlated fluid phase is identified, in which transport of classical charges exhibits correlated behavior. Freezing transitions into commensurate ground state configurations are found to be of the first order. A novel model of transport in disordered systems is proposed to account for experimentally observed current transients in dot arrays at high bias. This transport model yields a non-stationary response in a stationary system. The model proposes a particular power law noise spectrum that is found to be consistent with experiments. In Part II of the Thesis novel effects in Carbon nanotubes are predicted. These effects can be manifest in transport measurements. First, it is shown that a strong electric field applied perpendicularly to the tube axis can fracture the Fermi surface of metallic nanotubes and significantly reduce excitation gap in semiconducting nanotubes. The depolarization problem is linked to the chiral anomaly of 1+1 dimensional Dirac fermions. Second, coupling between a surface acoustic wave and nanotube electrons is proposed as a means to realize an adiabatic charge pump. Incompressible states are identified in the single particle picture, and the corresponding minigaps are found. Conditions for pumping experiment are identified.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Novikov, Dmitry S., 1976-

Advisor dc:contributor.advisor

• Leonid S. Levitov.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/39403

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/39403