Magnetic Semiconductors are attracting interest because of their potential use for spintronics. We h

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Ferromagnetic
Fe0.7Co0.3Si
Fe0.8Co0.2Si
0.96
Paramagnetic
Minority
0.95
Optical Reflectivity
0.94
Tc
Energy Landscape near bottom of FeSi conduction
band
Tc
0.93
Majority
0
100
200
0
100
200
Temperature (K)
Magnetic Semiconductors are attracting interest
because of their potential use for spintronics.
We have shown that a transition metal
monosilicide, Fe1-xCoxSi, a half metallic magnet
derived by doping the narrow gap semiconductor
FeSi is less reflective in the magnetic state
than above the transition temperature (TC). We
conclude that the carriers in the majority spin
sub-band scatter more strongly from the doping
induced corrugated potential landscape than those
in either the minority or paramagnetic bands due
to the increased depth of the potential wells.
2
Metal-Insulator Transition in Magnetic
Semiconductors
John F. DiTusa, Louisiana State University,
DMR-0406140
Power Law Exponent of the Conductivity near the
Insulator to Metal Transition
Broader impact Our ability to manipulate the
magnetic moments of electrons to the same extent
that we can their charge in modern device
technologies underpins the nascent technology of
spintronics. This research explores the
fundamental question of how a paramagnetic
semiconductor can be modified to exhibit
ferromagnetic and metallic properties and
searches for silicon-based materials for use in
spintronics. This figure displays the unusual
properties of the insulator to metal transition
in Mn doped FeSi.
1.5
H 0
1
T (K)
0.5
0
1.5
H 9 T
1
T (K)

• Education Undergraduate students Robert
  Anderson, Jakob Duran, Jon Hanson, Jon Hefner
  (computer science), Dung Lee, Becky Lefebvre,
  Andrew Morrow, Margaret Reaves (Chem E),
  Christopher Weaver, and Matthew Wolboldt and
  graduate students Song Guo and Rajan Rai all
  contribute to this research.

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