surface diffraction on magnetic nanostructures in thin films using grazing incidence sans. m....

Surface diffraction on magnetic nanostructures in thin films

using grazing incidence SANS.

M. Pannetier(a), F. Ott(b), C. Fermon(b), Y. Samson(c)

(a) DRECAM/SPEC, CEA Saclay, 91191 Gif sur Yvette FRANCE(b) Lab. Léon Brillouin CEA/CNRS, 91191 Gif sur Yvette FRANCE

(c) CEA Grenoble DRFMC/SP2M, 17 rue des Martyrs 38054 Grenoble France

Outline

Principle of the experiment

Scattering on a FePd system

Data simulations

Other prospective systems

Principle of the experiment

Under total reflection angle (c) an evanescent wave is travelling parallel to the surface

penetration depth 10-50 nm

i < c

ki kf

Scattering geometry

z

x y

neutrons

Incidence plane10-4 < Qy < 10-2 nm-1

600 nm < < 60 µm

incidence plane10-2 < Qy < 3 nm-1

10-1 nm < < 100 nm

Experimental set-up

Spectrometer PAPOL at the LLB Saclay

sampleslit 1H

Specular reflected beam

Incidence angle on the sample i

slit 2H

diffracted beam

polariser

Detector

Y

X

Z

FePd layers

Fe0.5Pd0.5 alloy layers “self-organise” in magnetic stripes

Domain sizes : 60 nmWall thickness : 6 nm

Magnetic domains

Field B = Hd + M

Simulation OOMMF

DRFMC CEA Grenoble

Magnetic sensitivity

Top view

ki

kf

qy

The domains magnetisation contribute to the scatteringNeel caps do not contributeBloch wall do contribute

Néel cap

Mup

Mdo

M and B components in the layerM B

X

Y

Z

-60

-40

-20

0

20

40

60

0

position

Fie

ld

Field Y

Field Z

-100

-50

0

50

100

0

position

Fie

ld

MagY

Mag Z

GID scattering on the PSD

c = 0.7°

Beam stop

diffraction

Specular line

Refracted signalQy

Qz

Calcul plus complet (facteur de forme inclus)

Sin(PhiF) vs Sin(Theta out) ; Theta In = 0.2° (stupide) Gauche ligne sur substrat; droite “vraie situation” (sauf épaisseur) Les échelles de couleurs ne corespondne tpas du tout au meme

intensités!!!

Problem of the stray fields

The stray fields are not negligible – They create a rather large magnetic potential

outside the layer

GID

2D grating (top view)

TF

Rods

2/d

d

Ewald sphere

ki

kf

ki

Other example : Co clusters in Al2O3

Co/Al2O3D.Babonneau et al, APL 76 (2000)

2/ 5.4nmGISANS

Correlationfonction

Formfactor