Spin depend electron transport amr gmr
This presentation is the property of its rightful owner.
Sponsored Links
1 / 31

Spin depend electron transport: AMR, GMR PowerPoint PPT Presentation


  • 73 Views
  • Uploaded on
  • Presentation posted in: General

Spin depend electron transport: AMR, GMR. Lecture 2. Magnetorezystancja. Anizotropowa Magnetorezystancja AMR origin spin – orbit coupling (  1960) Gigantyczna Magnetorezystancja GMR 1986 – oscillatory interlayer exchange coupling in Fe/Cr/Fe multilayers

Download Presentation

Spin depend electron transport: AMR, GMR

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Spin depend electron transport amr gmr

Spin depend electron transport: AMR, GMR

Lecture 2


Magnetorezystancja

Magnetorezystancja

Anizotropowa Magnetorezystancja AMR

origin spin – orbit coupling (1960)

Gigantyczna Magnetorezystancja GMR

1986 – oscillatory interlayer exchange coupling in Fe/Cr/Fe multilayers

P. Grünberg et al. Phys Rev.Lett. 57 (1986), 2442

1988 – GMR in Fe/Cr/Fe multilayers

M. N. Baibich,..., A.Fert,.. et.al. Phys Rev.Lett. 61 (1988), 2472


Spin depend electron transport amr gmr

  • Ohms law for galvanomagnetic effects

    m = M / |M|

    mx= sinq cosf

    my= sinq sinf

    mz= cosf,

  • magnetoresistivityDr = r- r


Spin depend electron transport amr gmr

Galvanomagnetic effects in the plane of thin film

  • Longitudinal magnetoresistivity effect

  • Transversal magnetoresistivity effect


Spin depend electron transport amr gmr

  • Angle dependence of the longitudinal magnetoresistivity

    U = R i

    U = Ri


Spin depend electron transport amr gmr

Magnetic field dependence of the longitudinal magnetoresistivity effect (AMR)

if i || Hq =f


G iant m agnetoresistivity gmr

I = const

Ua

magnetoresistance

-

-

U

U

R

R

D

R

a

p

a

p

=

=

»

%

5

100

U

R

R

p

p

p

Giant Magnetoresistivity - GMR

I = const

 10 nm

Up

ferromagnet

nonferromagnet (Cu)

ferromagnet


Thickness dependence of spacer layer

Thickness dependence of spacer layer


Spin depend electron transport amr gmr

GMR is isotropic in respect to the current


Spin depend electron transport amr gmr

Below, structure of Fe film/ Cr wedge/ Fe whisker illustrating the

Cr thickness dependence of Fe-Fe exchange. Above, SEMPA

image of domain pattern generated from top Fe film. (J. Unguris et

al., PRL 67(1991)140.)


Spin depend conductivity

M

M

I

R small

Spin depend conductivity

I

R large


Density of states in 3 d metals

Density of states in 3-d metals

GMR  due scattering into the empty quantum states above the Fermi level D(EF)

For ferromagnetic 3d metals D(EF)  D(EF)    


Spin polarization of ferrmagnets

Energy

Energy

Energia

EF

d

d

d

s

s

s

Spin

Spin polarization of ferrmagnets

Magnetization

Density of states


Pseudo spin valve psv m h r h

Pseudo spin valve (PSV) M(H) & R(H)

Two stages charactristics


Magnetic dots

Magnetic dots

Co (4nm)

Cu (3nm)

NiFe (6nm)


M agnetic r andom a ccess m emory mram

0

1

Magnetic Random Access Memory (MRAM)

ścieżka przewodząca

antyferromagnetyk

ferromagnetyki

nieferromagnetyczna

międzywarstwa

 150 nm


Zastosowania pseudo zawor w spinowych

Zastosowania pseudo-zaworów spinowych

  • Nieulotne pamięci magnetyczne o dostępie swobodnym (Magnetic Random Access Memory)

    • matryca złożona z komórek pamięciowych: elementów PSV

    • bit informacji reprezentowany poprzez wzajemną orientację wektorów namagnesowania warstw ferromagnetycznych twardej i miękkiej;

    • zapis poprzez przemagnesowanie silniejszym prądem;

    • odczyt poprzez detekcję zmiany rezystancji

    • informacja przechowywana jest po zaniku zasilania;

    • szybki zapis i odczyt, mały pobór mocy;

    • cykle zapisujące są nieniszczące;

    • odporność na promieniowanie jonizujące.


Spin valve sv

M(H) magnetization

Spin-Valve (SV)

R(H) magnetoresistance


Spin valve sv m h r h

Spin valve (SV) – M(H) & R(H)

high magnetoresistance field sensitivity


Different gmr structures

Different GMR Structures


Spin depend electron transport amr gmr

  • Conclusions

  • GMR can only be observedif at latest two ferromagnetic layers are separated by non-magnetic metal layers

  • GMR has a maximum, if the magnetization vectors in adjacent

  • F-layers is antiparallel

  • CPP has a larger effect than CIP

  • GMR is a direct image of the magnetic hysteresis

  • GMR is much larger than AMR

  • GMR increases with decreasing temperature

  • GMR depends on the number of F/M interfaces

  • For the GMR effect it is not important how the antiparallel orientation of the magnetization vectors in adjacent ferromagnetic layers is achivied (exchange bias F/AF or exchange coupling SAF)


  • Login