"Beta-NMR: magnetic resonance from thin films and buried interfaces."
Relatore: Andrew MacFarlane- Chemistry Department, Vancouver, Canada
04 Febbraio 2004 ore 16.30
|By virtue of the easy detectability of the high energy decay products of
nuclear disintegrations, radioactive nuclei have found many applications in
the study of condensed matter, particularly in situations where conventional
methods are hampered by the relative scarcity of the atoms of interest, for
example dilute impurities in semiconductors. Recently we have developed a
pair of beta-detected-NMR spectrometers employing the intense low energy
spin-polarized beams of radioactive ions available at the new ISAC facility
at TRIUMF. In this method, the nuclear magnetic resonance or relaxation is
detected through the anisotropic beta decay of the probe nucleus, yielding
the detailed local magnetic information familiar from conventional NMR
experiments, but using approximately 10 orders of magnitude fewer nuclei. By
electrostatic deceleration of the ion beam from its nominal energy of 30 keV,
we can vary the average implantation depth of the ions from a few hundred
nanometres down to a few nm. We plan to use this capability to study
ultrathin films and nanostructured materials, where there are many
interesting questions regarding, for example, the electronic and magnetic
properties of buried interfaces and nanoscale electronic confinement effects.
I will summarize our progress in this direction, and present an outlook for
the future of the technique.