Oscillating Antiferromagnetism of Ultrathin EuTe Layers

We study magnetic resonance on EuTe/PbTe superlattices. Analysis of the magnetic dipole anisotropy in the superlattices and of the EPR amplitude of isolated Eu ions in the PbTe wells shows that the diffusion at interfaces is very small. The real thickness of EuTe can be evaluated with an accuracy better than one monolayer. Since for EuTe layers thicker than 2 monolayers there is no difference in the character of the antiferromagnetic resonance observed for even and odd numbers of monolayers, we conclude that there is no static magnetization of the antiferromagnetic sublattices. Nevertheless, long range antiferromagnetic order is clearly evident.