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halfmetallicity

Half-metallicity is a property of certain materials in which electrons of one spin orientation behave as conducting, metallic electrons while electrons of the opposite spin experience a band gap and act as insulators or semiconductors at the Fermi level. In the ideal case this leads to 100 percent spin polarization of the conduction electrons, a feature that makes these materials attractive for spintronics.

In a half-metal, the electronic structure is spin-dependent: one spin channel has a metallic density of states

Materials commonly studied for half-metallicity include Heusler alloys, such as NiMnSb and Co2MnSi, which have been

Applications of half-metals are largely in spintronics, where highly spin-polarized currents can enhance the performance of

The concept was introduced in the 1980s by de Groot and colleagues, who predicted half-metallic ferromagnetism

at
the
Fermi
level,
while
the
other
channel
has
a
gap
or
a
very
low
density
of
states.
Real
materials
often
depart
from
this
ideal
picture
because
of
defects,
finite
temperature,
and
many-body
interactions,
which
introduce
states
in
the
gap
and
reduce
the
observable
spin
polarization.
predicted
and
observed
to
exhibit
high
spin
polarization.
Other
examples
include
certain
oxide
ferromagnets
like
CrO2
and
some
manganites
such
as
La0.7Sr0.3MnO3.
The
degree
to
which
a
given
material
is
truly
half-metallic
can
depend
on
synthesis,
crystallinity,
and
external
conditions.
devices
such
as
spin
valves,
magnetic
tunnel
junctions,
and
magnetoresistive
random-access
memory
(MRAM).
While
perfect
half-metallicity
is
rarely
realized
in
practice,
the
concept
remains
influential
for
designing
materials
with
large
spin
polarization
and
robust
spintronic
functionality.
in
NiMnSb
and
related
compounds.