<s>
Spinterface	B-General_Concept
is	O
a	O
term	O
coined	O
to	O
indicate	O
an	O
interface	O
between	O
a	O
ferromagnet	O
and	O
an	O
organic	B-Algorithm
semiconductor	I-Algorithm
.	O
</s>
<s>
In	O
particular	O
,	O
spinterfaces	B-General_Concept
are	O
widely	O
studied	O
in	O
the	O
scientific	O
community	O
because	O
of	O
their	O
hybrid	O
organic/inorganic	O
composition	O
.	O
</s>
<s>
The	O
field	O
of	O
spintronics	O
,	O
which	O
is	O
the	O
scientific	O
field	O
that	O
aims	O
to	O
study	O
the	O
spin-dependent	O
electron	O
transport	O
in	O
solid-state	O
devices	O
,	O
emerged	O
in	O
the	O
last	O
decades	O
of	O
the	O
20th	O
century	O
,	O
first	O
with	O
the	O
observation	O
of	O
the	O
injection	O
of	O
a	O
spin-polarized	O
current	O
from	O
a	O
ferromagnetic	O
to	O
a	O
paramagnetic	O
metal	O
and	O
subsequently	O
with	O
the	O
discovery	O
of	O
tunnel	O
magnetoresistance	B-General_Concept
and	O
giant	B-General_Concept
magnetoresistance	I-General_Concept
.	O
</s>
<s>
Only	O
more	O
recently	O
,	O
spintronics	O
has	O
been	O
extended	O
to	O
the	O
organic	O
world	O
,	O
with	O
the	O
idea	O
of	O
exploiting	O
the	O
weak	O
spin-relaxation	O
mechanisms	O
of	O
molecules	O
in	O
order	O
to	O
use	O
them	O
for	O
spin	O
transport	O
.	O
</s>
<s>
Research	O
in	O
this	O
field	O
started	O
off	O
with	O
hybrid	O
replicas	O
of	O
inorganic	O
spintronic	O
devices	O
,	O
such	O
as	O
spin	B-General_Concept
valves	I-General_Concept
and	O
magnetic	O
tunneling	O
junctions	O
,	O
trying	O
to	O
obtain	O
spin	O
transport	O
in	O
molecular	O
films	O
.	O
</s>
<s>
However	O
some	O
devices	O
did	O
n't	O
behave	O
as	O
expected	O
,	O
for	O
example	O
vertical	O
spin	B-General_Concept
valves	I-General_Concept
displaying	O
a	O
negative	O
magnetoresistance	B-General_Concept
.	O
</s>
<s>
It	O
was	O
then	O
quickly	O
understood	O
that	O
the	O
molecular	O
layers	O
do	O
n't	O
just	O
play	O
a	O
transport	O
role	O
but	O
they	O
can	O
also	O
act	O
on	O
the	O
spin	B-General_Concept
polarization	I-General_Concept
of	O
the	O
ferromagnet	O
at	O
the	O
interface	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
the	O
interest	O
on	O
ferromagnet/organic	O
interfaces	O
rapidly	O
increased	O
in	O
the	O
scientific	O
community	O
and	O
the	O
term	O
"	O
spinterface	B-General_Concept
"	O
was	O
born	O
.	O
</s>
<s>
In	O
particular	O
,	O
in	O
spinterfaces	B-General_Concept
,	O
a	O
metal	O
and	O
an	O
organic	B-Algorithm
semiconductor	I-Algorithm
,	O
which	O
display	O
very	O
different	O
electronic	O
properties	O
,	O
are	O
interfaced	O
and	O
they	O
usually	O
form	O
a	O
strong	O
hybridization	O
.	O
</s>
<s>
With	O
the	O
final	O
aim	O
of	O
being	O
able	O
to	O
tune	O
and	O
change	O
the	O
electronic	O
and	O
magnetic	O
behavior	O
of	O
the	O
interface	O
,	O
spinterfaces	B-General_Concept
are	O
studied	O
both	O
by	O
inserting	O
them	O
into	O
spintronic	O
devices	O
and	O
,	O
on	O
a	O
more	O
basic	O
level	O
,	O
by	O
investigating	O
the	O
growth	O
of	O
ultra-thin	O
molecular	O
layers	O
on	O
ferromagnetic	O
substates	B-Architecture
with	O
a	O
surface	O
science	O
approach	O
.	O
</s>
<s>
The	O
scope	O
of	O
building	O
such	O
interfaces	O
is	O
on	O
one	O
side	O
to	O
exploit	O
the	O
spin-polarized	O
character	O
of	O
the	O
electronic	O
structure	O
of	O
the	O
ferromagnet	O
to	O
induce	O
a	O
spin	B-General_Concept
polarization	I-General_Concept
in	O
the	O
molecular	O
layer	O
and	O
,	O
on	O
the	O
other	O
hand	O
,	O
to	O
influence	O
the	O
magnetic	O
character	O
of	O
the	O
ferromagnetic	O
layer	O
by	O
means	O
of	O
hybridization	O
.	O
</s>
<s>
Combining	O
this	O
with	O
the	O
fact	O
that	O
usually	O
molecules	O
have	O
a	O
very	O
high	O
responsivity	O
to	O
stimuli	O
(	O
typically	O
impossible	O
to	O
achieve	O
in	O
inorganic	O
materials	O
)	O
there	O
is	O
the	O
hope	O
of	O
being	O
able	O
to	O
easily	O
change	O
the	O
character	O
of	O
the	O
hybridization	O
,	O
hence	O
tuning	O
the	O
properties	O
of	O
the	O
spinterface	B-General_Concept
.	O
</s>
<s>
This	O
could	O
give	O
rise	O
to	O
a	O
new	O
class	O
of	O
spintronic	O
devices	O
,	O
where	O
the	O
spinterface	B-General_Concept
plays	O
a	O
fundamental	O
and	O
active	O
role	O
.	O
</s>
<s>
Organic	B-Algorithm
semiconductors	I-Algorithm
are	O
currently	O
used	O
in	O
various	O
applications	O
,	O
for	O
example	O
OLED	B-Device
displays	I-Device
,	O
which	O
can	O
be	O
flexible	O
,	O
thinner	O
,	O
faster	O
and	O
more	O
power	O
efficient	O
than	O
LCD	B-Device
screens	I-Device
,	O
and	O
organic	B-Algorithm
field-effect	I-Algorithm
transistors	I-Algorithm
,	O
intended	O
for	O
large	O
,	O
low-cost	O
electronic	O
products	O
and	O
biodegradable	O
electronics	O
.	O
</s>
<s>
In	O
terms	O
of	O
spintronic	O
applications	O
,	O
there	O
are	O
no	O
available	O
commercial	O
devices	O
yet	O
,	O
but	O
the	O
applied	O
research	O
is	O
headed	O
towards	O
the	O
use	O
of	O
spinterfaces	B-General_Concept
mainly	O
for	O
magnetic	O
tunneling	O
junctions	O
and	O
organic	O
spin	B-General_Concept
valves	I-General_Concept
.	O
</s>
<s>
The	O
physical	O
principle	O
that	O
is	O
mainly	O
exploited	O
when	O
talking	O
about	O
spinterfaces	B-General_Concept
is	O
the	O
spin-filtering	O
.	O
</s>
<s>
This	O
is	O
simply	O
schematized	O
in	O
figure	O
:	O
when	O
one	O
considers	O
the	O
ferromagnet	O
and	O
the	O
organic	B-Algorithm
semiconductor	I-Algorithm
on	O
their	O
own	O
(	O
panel	O
a	O
)	O
,	O
the	O
density	O
of	O
states	O
(	O
DOS	O
)	O
of	O
the	O
metal	O
will	O
be	O
unbalanced	O
between	O
the	O
two	O
spin	O
channels	O
,	O
with	O
the	O
difference	O
of	O
the	O
up	O
and	O
down	O
DOS	O
at	O
the	O
Fermi	O
level	O
governing	O
the	O
spin	B-General_Concept
polarization	I-General_Concept
of	O
the	O
current	O
flow	O
;	O
the	O
DOS	O
of	O
the	O
organic	B-Algorithm
semiconductor	I-Algorithm
will	O
have	O
no	O
unbalance	O
between	O
the	O
spin	O
channels	O
and	O
will	O
display	O
localized	O
energy	O
levels	O
,	O
namely	O
highest	O
occupied	O
molecular	O
orbital	O
(	O
HOMO	O
)	O
and	O
lowest	O
unoccupied	O
molecular	O
orbital	O
(	O
LUMO	O
)	O
,	O
with	O
zero	O
DOS	O
at	O
the	O
Fermi	O
Level	O
.	O
</s>
<s>
As	O
a	O
matter	O
of	O
example	O
,	O
panel	O
b	O
represents	O
the	O
case	O
of	O
a	O
parallel	O
injection	O
of	O
current	O
,	O
while	O
panel	O
c	O
schematizes	O
an	O
antiparallel	O
spin	B-General_Concept
polarization	I-General_Concept
of	O
the	O
current	O
injected	O
in	O
the	O
semiconductor	O
.	O
</s>
<s>
In	O
this	O
way	O
,	O
the	O
injected	O
current	O
will	O
be	O
polarized	O
accordingly	O
to	O
the	O
interface	O
DOS	O
at	O
the	O
Fermi	O
Level	O
and	O
exploiting	O
the	O
fact	O
that	O
molecules	O
usually	O
have	O
intrinsically	O
weak	O
spin-relaxation	O
mechanisms	O
,	O
molecular	O
layers	O
are	O
great	O
candidates	O
for	O
spin	O
transport	O
applications	O
.	O
</s>
<s>
By	O
a	O
good	O
material	O
choice	O
one	O
is	O
then	O
able	O
to	O
filter	O
the	O
spins	O
at	O
the	O
spinterface	B-General_Concept
.	O
</s>
<s>
Applied	O
research	O
on	O
spinterfaces	B-General_Concept
is	O
often	O
focused	O
on	O
studying	O
the	O
tunnel	O
magnetoresistance	B-General_Concept
(	O
TMR	O
)	O
in	O
hybrid	O
magnetic	O
tunneling	O
junctions	O
(	O
MTJs	O
)	O
.	O
</s>
<s>
The	O
idea	O
of	O
using	O
spinterfaces	B-General_Concept
consists	O
in	O
replacing	O
the	O
inorganic	O
insulating	O
barrier	O
with	O
an	O
organic	O
one	O
.	O
</s>
<s>
The	O
motivation	O
for	O
this	O
is	O
given	O
by	O
the	O
flexibility	B-Application
,	O
low	O
cost	O
and	O
higher	O
spin-relaxation	B-Algorithm
times	I-Algorithm
of	O
molecules	O
and	O
the	O
possibility	O
of	O
chemically	O
engineering	O
the	O
interfaces	O
.	O
</s>
<s>
By	O
changing	O
the	O
relative	O
orientation	O
of	O
the	O
magnetization	O
of	O
the	O
electrodes	O
it	O
is	O
possible	O
to	O
control	O
the	O
conductance	O
state	O
of	O
the	O
tunneling	O
junction	O
and	O
use	O
this	O
principle	O
for	O
applications	O
,	O
for	O
example	O
read-heads	B-Device
of	O
hard	B-Device
disk	I-Device
drives	I-Device
and	O
MRAMs	B-General_Concept
.	O
</s>
<s>
Barraud	O
et	O
al.	O
,	O
in	O
a	O
Nature	O
Physics	O
paper	O
,	O
develop	O
a	O
spin	O
transport	O
model	O
that	O
takes	O
into	O
account	O
the	O
effect	O
of	O
the	O
spinterface	B-General_Concept
hybridization	O
.	O
</s>
<s>
Conventional	O
spin	B-General_Concept
valves	I-General_Concept
are	O
built	O
in	O
a	O
very	O
similar	O
way	O
with	O
respect	O
to	O
magnetic	O
tunneling	O
junctions	O
,	O
the	O
difference	O
is	O
that	O
the	O
two	O
ferromagnetic	O
electrodes	O
are	O
this	O
time	O
separated	O
by	O
a	O
non-magnetic	O
metal	O
instead	O
of	O
an	O
insulator	O
.	O
</s>
<s>
When	O
the	O
current	O
enters	O
another	O
ferromagnetic	O
material	O
,	O
the	O
relative	O
orientation	O
of	O
the	O
magnetization	O
with	O
respect	O
to	O
the	O
first	O
electrode	O
can	O
lead	O
to	O
a	O
change	O
in	O
the	O
resistance	O
of	O
the	O
junction	O
:	O
if	O
the	O
alignment	O
of	O
the	O
magnetizations	O
is	O
parallel	O
,	O
the	O
spin	B-General_Concept
valve	I-General_Concept
will	O
exhibit	O
a	O
low	O
resistance	O
state	O
,	O
while	O
,	O
in	O
the	O
case	O
of	O
antiparallel	O
alignment	O
,	O
reflection	O
and	O
spin	O
flip	O
scattering	O
events	O
give	O
rise	O
to	O
a	O
high	O
resistance	O
state	O
.	O
</s>
<s>
From	O
these	O
considerations	O
one	O
can	O
define	O
and	O
evaluate	O
the	O
magnetoresistance	B-General_Concept
of	O
the	O
spin	B-General_Concept
valve	I-General_Concept
:	O
</s>
<s>
The	O
usual	O
way	O
of	O
creating	O
the	O
possibility	O
of	O
having	O
both	O
parallel	O
and	O
antiparallel	O
alignment	O
is	O
either	O
pinning	O
one	O
of	O
the	O
electrodes	O
by	O
means	O
of	O
exchange	O
bias	O
or	O
directly	O
using	O
different	O
materials	O
with	O
different	O
coercive	O
fields	O
for	O
the	O
two	O
electrodes	O
(	O
pseudo	O
spin	B-General_Concept
valves	I-General_Concept
)	O
.	O
</s>
<s>
The	O
proposed	O
use	O
of	O
spinterfaces	B-General_Concept
in	O
spin	B-General_Concept
valve	I-General_Concept
applications	O
is	O
to	O
interface	O
one	O
of	O
the	O
electrodes	O
with	O
a	O
molecular	O
layer	O
,	O
which	O
is	O
capable	O
of	O
tuning	O
the	O
magnetization	O
properties	O
of	O
the	O
electrode	O
with	O
a	O
change	O
in	O
hybridization	O
.	O
</s>
<s>
This	O
change	O
of	O
hybridization	O
at	O
the	O
spinterface	B-General_Concept
can	O
be	O
induced	O
in	O
principle	O
both	O
by	O
light	O
(	O
making	O
these	O
systems	O
suitable	O
for	O
ultra-fast	O
applications	O
)	O
and	O
electric	O
voltages	O
.	O
</s>
