FORMATION AND TRANSFORMATION OF ANTIFERROMAGNETIC DOMAINS IN METALLIC 
MULTILAYERS: THE REFLECTOMETRIC APPROACH 
D.L. NAGY, L. BOTTYÁN, L. DEÁK, M. MAJOR and E. SZILÁGYI 
KFKI Research Institute for Particle and Nuclear 
Physics, Budapest, Hungary, 
nagy@rmki.kfki.hu 

ABSTRACT The magnetocrystalline anisotropy in antiferromagnetically (AF)
coupled metallic multi-layers may lead to spectacular effects, which can
be most efficiently studied by two closely related nuclear scattering
techniques, namely synchrotron Mössbauer reflectometry (SMR) and polarised
neutron reflectometry (PNR). A spin-flop transition takes place in a
strongly AF-coupled epitaxial Fe/Cr multilayer of fourfold in-plane
anisotropy when a moderate magnetic field is applied along the easy axis
in which the layer magnetisations actually lay. The electronically
forbidden AF reflections in a specular SMR experiment fully appear or
completely disappear during the spin-flop transition. In case of specular
PNR, the AF re-flection moves from the spin-flip to the non-spin-flip
channel on spin-flop transition or vice versa. The off-specular SMR and
PNR techniques are sensitive to the in-plane correlation length x of the
layer magnetisation direction and are, thereby, able to map the size
distribu-tion of the AF domains in multilayers. A dramatic increase of x
from about 1 mm to at least 10 mm, i.e., a coarsening of the AF domains
was observed in the same multilayer when it passed the spin-flop
transition provided that the external magnetic field was previously
de-creased from magnetic saturation to zero. This shows the key role of
the in-plane magneto-crystalline anisotropy in the domain-coarsening
process. Finally we demonstrate how the formation of sub-micrometer
domains can be followed by SMR and PNR. 

Keywords: Multilayers, antiferromagnetic coupling, domains, synchrotron
Mössbauer reflectometry, polarised neutron reflectometry