Magnetic Properties of Semiconductor-Antiferromagnet Superlattices

Magnetic resonance investigations of ultra-thin antiferromagnetic EuTe layers show a specific behaviour in the quasi-2D antiferromagnetic ordering: (i) an anisotropy of the critical broadening, (ii) a substantial increase in the Néel temperature and (iii) an anisotropic shift of the resonance frequency which diverges at the Néel point. The results show that exchange coupling is stronger in quasi-2D than in 3D antiferromagnetic samples and that correlation of spin chains aligned in the perpendicular direction occurs already well above the Néel point.