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    Influence of spinon conduction

    Magneticnanostructures

    Memory (M-RAM)

    GMR, TMR, etc

    Spintronics

    Spin up electron

    Spin down electron

    Albert Fert, UMR CNRS/Thales, Palaiseau, and Universit Paris-Sud, Orsay, France

    Magnetic switching

    and microwave

    generationbyspin

    transfer, spintronics

    withsemiconductors,

    molecular spintronics,

    etc

    The origin, the development and the future of

    spintronics

    spin

    charge

    lectron

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    E

    EF

    n (E)

    n (E)

    Spin dependent conduction in ferromagnetic metals(two

    current model)Mott, ProcRoy!oc A"#$, "%$&

    Fert et al, PR' ", ""%, "%&*

    'oegel-+autier, P! $, "%."

    Fert et al,PhysF&, */%, "%.&

    0orle1in et al, i2id F., $, "%..

    I

    I = / or= (- )/ (+ )

    = (- 1)/(+ 1)

    E

    EF

    n (E)

    n (E)

    3i d 2andr dlevel

    4irtual

    2ound

    state

    0.3

    20

    r dlevel

    3i d 2and

    5i 4 r Mn Fe o 3i

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    Mixing impriti!s " and # with opposit! or simi$ar spin asymm!tri!s% the

    pre-concept of GMR

    Example: Ni + impuritiesand!(Fert-Campbell, 1968, 1971)

    "st case #d

    caseA 6 ", 78 " A and76 "$igh mo%ilit& channel low

    A7 66 A9 7 A7A9 7

    spin

    spin

    spin

    spin

    &. d! 'hysi! 32 1*1

    :;

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    Molecular Beam Epitaxy(growt of metallic multilayers!

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    "e

    "e

    #r

    #r

    $Magnetic multilayers

    "e

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    "e

    "e

    #r

    #r

    Magneti%ations of"e layers at %ero fieldin "er multilayers

    $Magnetic multilayers

    "e

    P. Grnberg, 1986 antiferromagnetic interlayer coupling

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    "e

    "e

    #r

    #r

    Magneti%ations of

    "e layers in anapplied field

    in "er multilayers

    $Magnetic multilayers

    "e

    Read head of

    hard disc drive

    GMR sensor# nm

    Ma"netic #ields

    "enerated by the $edia

    "%%. (2efore +MR) = " +2it;in,. = +MR heads ? $ +2it;in

    ,o$tag!

    crr!nt

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    Arrays of +MR 2iochips for analysis of

    2iomolecules ( [email protected]= antigens are trapped 2yanti2odies and also decorated 2y other anti2odies

    la2elled 2y magnetic nanoparticles which are

    detected 2y a +MR sensor)

    % m (Philips), "m (!anta 7ar2ara)

    Pro2e arrays foranalysis of thousandsof different targets in

    parallel

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    ? " nm

    $!agnetic Tunnel "unctions,Tunneling !agnetoresistance#T!$%

    Low resistance state High resistance state

    ferromagnetic electrodes

    tunnelingbarrier

    (insulator)"'

    '

    % d!nsity/sp!!d o"M/"M +

    non,o$ati$ty + $ow

    !n!rgy consmption

    Applications: - read heads of Hard Disc Drive

    - M-RAM (Magnetic Random Access Memory)

    MRAM

    !oodera et al, 199&, !iyasa'i et al,199&,o(e)*l+-)o, !$ -/0

    "ulli2re, 193&,

    lo4 T, hardly

    reproducible

    0.1 m

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    irst !xamp$!s on !/Mg/!(001)%

    4/5ha$!s (#ow!n " !t a$

    "'62001) 4ancy (ar!-7inc!nt !t a$

    "'6 2003) 5s8ba (9asa !t a$ 4atr!

    Mat. 200:) I#M ('ar8in !t a$ 4atr!

    Mat. 200:) ;.!tc

    Epitaxial magnetic tunnel 'unctions (Mg etc)

    uasa et al, Fe;MgB;Fe

    4atr! Mat. 200:

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    Mathon and Hmers>i, PR 7 "%%%

    Mavropoulos et al, PR' 7utler

    et al , PR 7 "

    Ihang and 7utler, PR 7 / >bcc

    o/Mg/bcc o(001)?

    P

    AP 1

    [email protected]

    1

    :

    :[email protected]

    Ah d # $ ' # 200B B d M O

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    Ahang and #t$!r ' # 200B

    P

    AP 1

    [email protected]

    1

    :

    :

    [email protected]

    !g, 5ne (Mavropoulos et al, R! "###),etc

    1symmetry #sp% slo4ly decaying

    tunneling of oma7ority spinelectrons

    rTi- and otherd/bonded insulators

    ($elev et al , R! %&, "##&' oen et al, R

    "##*)

    &symmetry #d% slo4ly decaying

    tunneling ofo minority spinelectrons

    in agreement 4ith the negative

    polariation of ofound in T!$ 4ith

    rTi- ,Ti+and e1/:a+barriers

    (de +eresa, A et al, .cience /%%%)

    Beyond MgO

    Ah d # t$ ' # 200B B d M O

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    Ahang and #t$!r ' # 200B

    P

    AP

    !g, 5ne (Mavropoulos et al, R! "###),etc

    1symmetry #sp% slo4ly decaying

    tunneling of oma7ority spinelectrons

    rTi- and otherd/bonded insulators

    ($elev et al , R! %&, "##&' oen et al, R

    "##*)

    &symmetry #d% slo4ly decaying

    tunneling ofo minority spinelectrons

    in agreement 4ith the negative

    polariation of ofound in T!$ 4ith

    rTi- ,Ti+and e1/:a+barriers

    (de +eresa, A et al, .cience /%%%)

    Beyond MgO

    1

    [email protected]

    1

    :

    :[email protected] basis %# & spin

    polariation '(P)

    ;Tunneling

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    pin Transfer#magnetic s4itching, micro4ave generation%

    pintronics 4ith semiconductors

    pintronics 4ith molecules

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    >ntroductionP%/G!$

    (M%sca, AF et al, MMM ..)

    !$ratio#1%

    0 nm

    6 nm

    C%/Cu urrent to Plane #PP% G!$(0Pirau1, AF et al, AP0 .2,MMM .)

    >P/G!$

    scaling length ? mean free path

    PP/G!$scaling length ? spin diffusion

    length @@ mean free path

    spin accumulation theory,

    (3alet-Fert, PR 4 .5)

    6 nm

    S i i j ti / t ti t NM/FM i t f

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    FM

    sfl = spin dision $!ngth in M

    = spin dision $!ngth in 4MNM

    sfl

    Spin injection/extraction at a NM/FM interface (beyond ballistic range)

    NM FM

    zone of spin

    accumulation

    NM

    sfl

    FM

    sfl

    EF

    EF=spinchemical potential

    Spin accumulation

    = EF-EF

    Spin current= J-J

    EF-EF~ exp(z/ ) in FMFM

    sfl

    EF-EF~ exp(-z/ ) in NMNM

    sfl

    NM

    sfl

    FM

    sfl

    EF

    = spinchemical potential

    E

    J-J

    J+J= current spin polarization

    (illustrati%n in the si$+lest

    case 6 #lat band, l%7 current,

    n% inter#ace resistance,

    sin"le +%larity)

    (!xamp$!% 0.: m in C10m in carbon

    nanotb!)

    S i i j ti / t ti t S i d t /FM i t f

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    NM= metal orsemiconducto

    r

    FM

    zone of spinaccumulation

    NM

    sfl

    FM

    sfl

    EF

    EFSpin accumulation= EF-EF

    Spin current= J-J

    NM

    sfl

    FM

    sfl

    EF

    E

    A!? metal

    emiconductor) ( metal

    >f similar spin spliting on both sidesbut much larger density of states in

    ( metal

    much larger spin accumulation

    density

    and much more spin flips

    on magnetic metal side

    almost complete depolariation of

    A! ?

    semiconductor

    1) situation withoutinterface resistance

    ( conducti!ity "is"atch #)

    (Sch"idt et al$ %& ' )

    Spin injection/extraction at a Se"iconductor/FM interface

    S i i j ti / t ti t S i d t /FM i t f

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    NM=semiconducto

    r

    EF

    asbah ' # 2000

    ".-&arDs ' # 2001

    Spin accumulation

    = EF-EF

    NM

    sfl

    FM

    sfl

    EF

    Current Spinolarization

    (J-J)/(J+J)

    FM spin dependent. interf.

    resist. #e

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    !pin transfer

    ( !loncews>i, MMM "%%&, ' 7erger, PR 7 "%%&)

    !

    81C%balt/C%++er/C%balt

    ! i t f

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    !pin transfer

    ( !loncews>i, MMM "%%&, ' 7erger, PR 7 "%%&)

    !

    STorCue on !#!!%

    81C%balt/C%++er/C%balt

    *he transerse component of the

    spin current is a%sor%ed and

    transferred to the total spin of thela&er

    F M x (M x M0)

    = periments on pillars

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    M!ta$$ic pi$$ar :0x1:0nmG

    "

    I - 7 -

    / nm" nm

    (ree ferro

    (ie

    d

    ferro

    u

    5nn!$ Fnction

    "

    I - 7 -

    / nm" nm

    (ree ferro

    (ied

    ferro

    barrier

    =periments on pillars

    a% (irst regime #lo4 D%!%

    b% econd regime #high D%