PhD Dissertation Defense of Joseph Sulpizio

Joey Sulpizio jopizio at
Mon Nov 1 13:57:20 PDT 2010



Ph.D. Candidate:  Joseph A. Sulpizio

Research Advisor:  David Goldhaber-Gordon

Date:  Wednesday, November 3, 2010
Time:  9AM
Location: McCullough 335

Title:  Ballistic Transport in Quantum Hole Wires

Abstract:  Recent experiments on ballistic electron transport in
semiconductor nanowires have revealed a rich set of phenomena
associated with one-dimensional (1D) quantum systems.  In this thesis,
we present measurements of hole transport in ballistic quantum wires
fabricated by GaAs/AlGaAs cleaved-edge overgrowth (CEO), as hole
transport in GaAs is expected to exhibit enhanced effects of
electron-electron interactions and spin-orbit coupling as compared
with transport of electrons.  To interpret these results, we have
developed a new, broadly-applicable approach to analyzing the
transport measurements of a ballistic 1D quantum system.  We validate
our analysis approach using nonlinear conductance data of both
electron and hole CEO quantum wires, where we find evidence for the
importance of charge interactions.  Applying our analysis to
measurements of hole transport in magnetic field, we find strong
g-factor anisotropy, which we associate with spin-orbit coupling.
Finally, we present the first observation of a predicted "spin-orbit
gap" in the 1D density of states, where counter-propagating spins are
accompanied by a clear signal in the conductance.

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