  We report results on the temperature dependence of the susceptibilities of a
set of MBE-grown short-period EuTe/PbTe antiferromagnetic superlattices having
different EuTe layer thicknesses. In-plane and orthogonal susceptibilities have
been measured and display a strong anisotropy at low temperature, confirming
the occurrence of a magnetic phase transition in the thicker samples, as seen
also in neutron diffraction studies. We suggest that dipolar interactions
stabilize antiferromagnetic long-range order in an otherwise isotropic system
and we present numerical and analytical results for the low-temperature
orthogonal susceptibility.
