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