2005 7th Annual Meeting of the Northwest Section
Friday–Saturday, May 13–14, 2005;
Victoria, BC, Canada
Session B1: Condensed Matter I
2:00 PM–4:49 PM,
Friday, May 13, 2005
MacLaurin
Room: D110
Chair: Byoung-Chul Choi, University of Victoria
Abstract ID: BAPS.2005.NWS.B1.1
Abstract: B1.00001 : Electron-Nuclear Spin Coupling in Semiconductor Quantum Wells*
2:00 PM–2:36 PM
Preview Abstract
Abstract
Author:
G.M. Steeves
(University of Victoria)
The ability to manipulate and detect nuclear spin orientation is
the basis for the
science of nuclear magnetic resonance (NMR). An exciting
application of NMR is
three dimensional magnetic resonance imaging (MRI) microscopy,
which recently
achieved ~$4\mu m\times 3\mu m\times 3\mu m$ resolution with a
nuclear spin
sensitivity of $~ 3\times10^{12}$ protons. In that application
and in most MRI
applications nuclear spin is used as a non-invasive probe; the
net nuclear
polarization does not disturb the characteristics of the sample.
Quite the reverse
can be true in the spintronic systems studied here (where
electron spin dynamics
are monitered and manipulated). The electron-nuclear hyperfine
coupling means,
for example, that nuclear polarization can dominate over external
magnetic fields in
determining the spin precession frequency of electrons in a GaAs
quantum well.
This strong coupling suggests that we can use spintronic systems
as sensitive
probes of nuclear spin polarization. Furthermore by controlling
electron spin and
electron-nuclear spin coupling we can manipulate local nuclear
fields. Working in
GaAs/AlGaAs coupled quantum wells (CQWs) and parabolic quantum
wells (PQWs),
we present several approaches for controlling the
electron-nuclear spin coupling.
By controlling the position of electron spins in a PQW and by
controlling the electron
nuclear spin coupling between these electron spins and lattice
nuclei we produce
thin ($<$10 nm wide) distributions of polarized nuclei. Applying
time-varying RF
fields across the electrical gates of our samples, we induce
local resonant nuclear
spin transitions of selected isotopes. Gaining nuclear spin
control in these systems
may allow us to utilize long nuclear spin coherence times in
spintronic application.
Also by controlling nuclear spin distributions on nanometer
length scales, we can
dynamically modify the electron spin environment.
*Supported by DARPA and NSF
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.NWS.B1.1