<s>
In	O
particle	O
physics	O
,	O
spin	B-General_Concept
polarization	I-General_Concept
is	O
the	O
degree	O
to	O
which	O
the	O
spin	O
,	O
i.e.	O
,	O
the	O
intrinsic	O
angular	O
momentum	O
of	O
elementary	O
particles	O
,	O
is	O
aligned	O
with	O
a	O
given	O
direction	O
.	O
</s>
<s>
Spin	B-General_Concept
polarization	I-General_Concept
of	O
electrons	O
or	O
of	O
nuclei	O
,	O
often	O
called	O
simply	O
magnetization	O
,	O
is	O
also	O
produced	O
by	O
the	O
application	O
of	O
a	O
magnetic	O
field	O
.	O
</s>
<s>
Spin	B-General_Concept
polarization	I-General_Concept
is	O
also	O
important	O
for	O
spintronics	O
,	O
a	O
branch	O
of	O
electronics	O
.	O
</s>
<s>
The	O
spin	O
of	O
free	O
electrons	O
is	O
measured	O
either	O
by	O
a	O
LEED	O
image	O
from	O
a	O
clean	O
wolfram-crystal	O
(	O
SPLEED	O
)	O
or	O
by	O
an	O
electron	O
microscope	O
composed	O
purely	O
of	O
electrostatic	O
lenses	O
and	O
a	O
gold	O
foil	O
as	O
a	O
sample	O
.	O
</s>
<s>
The	O
circular	O
polarization	O
of	O
electromagnetic	O
fields	O
is	O
due	O
to	O
spin	B-General_Concept
polarization	I-General_Concept
of	O
their	O
constituent	O
photons	B-Application
.	O
</s>
<s>
In	O
the	O
most	O
generic	O
context	O
,	O
spin	B-General_Concept
polarization	I-General_Concept
is	O
any	O
alignment	O
of	O
the	O
components	O
of	O
a	O
non-scalar	O
(	O
vectorial	O
,	O
tensorial	O
,	O
spinor	O
)	O
field	O
with	O
its	O
arguments	O
,	O
i.e.	O
,	O
with	O
the	O
nonrelativistic	O
three	O
spatial	O
or	O
relativistic	O
four	O
spatiotemporal	O
regions	O
over	O
which	O
it	O
is	O
defined	O
.	O
</s>
