ANNUAL REPORT - MTA SzFKI

I 25
4
3
Fig. 2. Average intensity of the 2 nd and 5 th lines
of the magnetic components as a function of
temperature for the x=0.4 (diamonds), 0.5
(triangles), 0.6 (circles), and 0.7 (squares)
[Ag(2.6 nm)/ 57 Fe(x nm)] 10 samples.
2
1
0
0 50 100 150 200 250 300
T [K]
direction occurs around x=0.6. It should be noted that for each sample the spectra were
evaluated as a sum of magnetic and non-magnetic components, the ratio of latter gradually
decreasing with decreasing temperature. For samples of x=0.4, 0.5, and 0.7, a slight
decrease of the average I 25 of the magnetic components can be observed with decreasing
temperature. It hardly exceeds the uncertainty arising from the correlation of line width
and amplitude values and might be due to stress induced by heat dilatations of the different
layers. Nevertheless, the observed temperature dependence cannot explain the rather sharp
change in the anisotropy direction as a function of layer thickness. The largest temperature
variation of I 25 is observed below 150 K for x=0.6, which is probably close to the width
where the crossover between the anisotropy directions occurs and that way the most
effected by thickness fluctuations of the layers.
These studies undoubtedly show that the appearance of the perpendicular anisotropy at
around x=0.6 is an intrinsic property of our Fe-Ag multilayers. It is not due to the stress
arising from the temperature variation, application of a capping layer or the sample
removal process. Our preliminary results on granular alloys of similar Fe concentration
and blocking temperature prepared by co-evaporation of the elements indicate that the out
of plane spontaneous magnetization is related to the layered structure.
E-Mail:
Imre Vincze
Sára Judit Balogh
László Bujdosó
Dénes Kaptás
Tamás Kemény
László Ferenc Kiss
vincze@szfki.hu
baloghj@szfki.hu
bujdi@szfki.hu
kaptas@szfki.hu
kemeny@szfki.hu
kissl@szfki.hu
Grants and international cooperations
OTKA T 048965 Magnetic properties of multilayer structures (J. Balogh, 2005-2008)
OTKA T046795 Superferromagnetism in nanostructures (I. Vincze, 2004-2007)
OTKA K68612 Magnetic anisotropy of structures with reduced dimension (L.F. Kiss,
2007-2010)
Hungarian-Spanish Academic Exchange Programme (Study of magnetocaloric effect in
amorphous alloys and nanostructures, L.F. Kiss, 2007-2008)
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