University
of California, Davis
Physics
Department
Colloquium
Dr. Frances
Hellman
" Spin
Electronics:
Magnetic Moments and Amorphous Semiconductors"
Spin
electronics in its broadest definition is
the study of systems where both the charge and the spin of the electron
play a
role. The charge of the electron usually is important because we
measure
currents and voltages. The spin of the electron is most obviously
seen
only in magnetic materials. Examples of spin electronics range
from
technological ideas such as MRAM (magnetic random access memory) which
are
based on magnetic tunnel junctions, to some forms of quantum
computing. I
will discuss efforts to introduce magnetic moments into semiconducting
materials, focusing particularly on our work on amorphous Si doped with
magnetic ions such as Gd. These alloys possess dramatic magnetic
and
transport properties due to electron-electron and electron-local moment
interactions, including enormous (many orders of magnitude) negative
magnetoresistance.