Condensed Matter Seminar Series
Title: h/e Magnetic Flux Modulation of the Energy Gap and
Weak Coulomb Blockade
Phenomena in Nanotube Quantum Dots
Ulas Coskun
University of Illinois, Urbana-Champagne
Tuesday Dec 13 (NOTE non-standard day!), 11:30 am, Room 234, Physics Building
Abstract: Multiwall carbon nanotubes are placed between two electrodes, source and
drain. Energy spectrum of the nanotubes is studied through differential
conduction measurements as a function of coaxial magnetic field.
Experimental results of the tubes acting as single-electron-tunneling (SET)
transistor suggest that there exists an interconversion between gapped
(semiconducting) and ungapped (metallic) states. The interconversion has a
period of h/e magnetic flux. The magnetic flux dependence of the energy
spectrum is found broadly in agreement with simple tight-binding
calculations. In addition temperature dependence of conductivity of the SET
transistors shows that Coulomb blockade is still effective at temperature
much larger than the charging energies.
Host: G. Finkelstein